JP2021163724A - Lighting device and display device - Google Patents

Abstract

To improve luminance uniformity.SOLUTION: A lighting device 12 includes: a light guide plate 15 shaped like a plate and configured so that a part of an outer peripheral end face is a light incident end face 15A for making light incident and one plate surface is a light emitting plate surface 15B for emitting light; a plurality of light sources 13 arrayed along the light incident end face 15A; and a plurality of light condensation portions 21A formed on a light emitting plate surface 15B of the light guide plate 15, extended along a first direction along a normal direction of the light incident end face 15A, arrayed along a second direction along an arrangement direction of the plurality of light sources 13 to provide straightness to light propagating in the light guide plate 15 so as to advance along the first direction. The plurality of light condensation portions 21A includes a first light condensation region A1 and a second light condensation region A2 arranged on the light source 13 side in the first direction rather than the first light condensation region A1 to provide higher straightness of light than the first light condensation region A1.SELECTED DRAWING: Figure 9

Description

The techniques disclosed herein relate to lighting devices and display devices.

Conventionally, the one described in the following Patent Document 1 is known as an example of a lighting device used for a liquid crystal display device or the like. The planar illuminating device, which is the illuminating device described in Patent Document 1, includes a light guide plate, a light source, an incoming light prism, a vertical prism, and an optical path changing portion. The light guide plate has a side surface serving as an incoming light surface and two main surfaces. One light source includes a plurality of light emitting elements having different emission colors, and a plurality of light sources are provided along the light entry surface. The light entry prism is provided on the light entry surface and allows a part of the light from the light source to travel in the first direction, which is a direction close to the direction substantially parallel to the light entry surface, and is the first direction of the light from the light source. Light other than the light that has traveled to the light source is traveled in the second direction, which is a direction substantially perpendicular to the light entering surface. The vertical prism extends in a direction substantially perpendicular to the light entering surface, and is provided on one of the two main surfaces so as to have a continuous uneven shape in a cross section intersecting the extending direction. The optical path changing portion is provided on the other main surface of the two main surfaces, and changes the optical path of the light inside the light guide plate.

Japanese Unexamined Patent Publication No. 2020-21640

The vertical prism provided on the exit surface of the light guide plate provided in the planar illumination device described in Patent Document 1 described above is for irregularly diffusing light in a direction substantially parallel to the entrance surface. Will be done. However, if the light is diffused irregularly as described above, the utilization efficiency of the light is lowered, and the brightness of the emitted light may be lowered. To avoid this, change the configuration of the vertical prism to give the light straightness so that it travels in a direction substantially perpendicular to the light entering surface, thereby improving the light utilization efficiency and improving the brightness. It is planned. On the other hand, for example, when a plurality of light sources are installed, the following problems may occur. That is, when the arrangement of a plurality of light sources with respect to the light entry surface of the light guide plate is uneven, the amount of light incident on the light entry surface from the light source far from the light entry end surface is reduced, so that the direction is substantially perpendicular to the light entry surface. There is a risk of band-shaped dark areas along the line. In order to make it difficult to see such a band-shaped dark portion, it is conceivable to reduce the straightness imparted to the light by the vertical prism. However, this in turn makes it easier for light to diffuse in a direction substantially parallel to the incoming surface, so that light incident on the incoming surface from multiple light sources overlaps in the vicinity of the incoming surface, resulting in locally bright bright areas. There is a risk.

The technique described in the present specification has been completed based on the above circumstances, and an object thereof is to improve the brightness uniformity.

(1) The lighting device according to the technique described in the present specification is a plate-shaped light emitting plate in which at least a part of the outer peripheral end surface is an incoming light incident surface and one plate surface emits light. A light guide plate as a surface, a plurality of light sources arranged along the light incoming end surface, and a plate surface opposite to the light emitting plate surface of the light guide plate and the light emitting plate surface. A condensing unit provided on one side, which extends along a first direction along the normal direction of the light incoming end face, and a plurality of light condensing portions are arranged along a second direction along the arrangement direction of the plurality of light sources. The light condensing unit is provided with a condensing unit that imparts straightness so as to travel along the first direction with respect to the light propagating in the light guide plate. A first condensing region and a second condensing region that is arranged on the light source side in the first direction with respect to the first condensing region and imparts higher straightness to light than the first condensing region. And are included.

(2) In addition to the above (1), the illuminating device includes a plurality of cylindrical lenses having an arcuate peripheral surface in the plurality of condensing portions, and the plurality of the cylindrical lenses include. Even if the second condensing region is configured to be larger than the first condensing region with respect to the contact angle, which is the angle formed by the tangent line at the base end portion on the peripheral surface with respect to the second direction. good.

(3) Further, in addition to the above (2), in the above-mentioned illuminating device, the plurality of the cylindrical lenses have the contact angle in the range of 30 ° to 50 ° in the first condensing region, whereas the contact angle is in the range of 30 ° to 50 °. The contact angle in the second condensing region may be in the range of 55 ° to 70 °.

(4) Further, in addition to the above (2) or the above (3), the illuminating device may include the plurality of the cylindrical lenses exclusively in the plurality of the condensing units.

(5) In addition to the above (2) or (3), the illuminating device includes a plurality of the cylindrical lenses in the plurality of the condensing portions, and an arcuate peripheral surface in the first condensing region. The second condensing region may include a plurality of composite lenses having a peripheral surface including a top portion and a pair of hypotenuses sandwiching the top portion.

(6) In addition to the above (5), the illuminating device has a plurality of the cylindrical lenses and the composite lens having a tangent line at the proximal end portion on the peripheral surface of the first condensing region. The contact angles, which are the angles formed in the two directions, may be the same.

(7) Further, in addition to the above (5) or the above (6), the illuminating device is arranged such that the cylindrical lens and the composite lens are alternately and repeatedly arranged in the second direction in a plurality of the condensing units. May be configured.

(8) Further, in addition to any of the above (5) to (7) in the above-mentioned lighting device, the plurality of the composite lenses have an angle formed by the pair of hypotenuses in the second condensing region. It may be in the range of 80 ° to 100 °.

(9) Further, in addition to any one of the above (1) to (8), the light guide plate is a first one in which the first light collecting region of the plurality of light collecting portions is located. It has a light guide unit and a second light guide unit in which the second light collection region of the plurality of light collection units is located, and the second light guide unit is the first light guide unit. The plate thickness may be smaller than that.

(10) Further, in addition to the above (1) to (9), the plurality of the light collecting units include the first light collecting region and the second light collecting region. The arrangement pitches in the two directions may be equal.

(11) Further, in addition to any of the above (1) to (10), the lighting device is provided with a second collection provided on the other side of the opposite plate surface and the light emitting plate surface of the light guide plate. A light unit that extends along the first direction and is arranged side by side along the second direction in the first direction with respect to light propagating in the light guide plate. A second light condensing unit may be provided that imparts straightness so as to proceed along the line.

(12) Further, in addition to any of the above (1) to (11), the lighting device is a light emitting reflecting portion provided on the other side of the opposite plate surface and the light emitting plate surface of the light guide plate. The light emitting reflecting unit may be provided, which includes a plurality of unit reflecting units that are arranged at intervals along the first direction and reflect light to be emitted from the light emitting plate surface.

(13) In addition to the above (12), the illuminating device has the first direction on the opposite plate surface of the light guide plate and the light emitting plate surface on which the light emitting reflecting portion is arranged. A sloped surface is provided so as to be adjacent to the unit reflecting portion and the distance from the plate surface on which the light emitting reflecting portion is not installed increases as the distance from the light source increases. Is arranged on the light source side in the first direction and inclined with respect to the first direction, and the unit reflection unit is arranged on the opposite side to the first reflection surface. The light guide plate has a second reflecting surface that is inclined, and the light guide plate is configured such that the inclination angle with respect to the first direction increases in the order of the inclined surface, the first reflecting surface, and the second reflecting surface. You may.

(14) The display device related to the technique described in the present specification includes the lighting device according to any one of (1) to (13) above and a display panel that displays using the light from the lighting device. And.

(15) Further, in addition to the above (14), the display device has a display area on which an image is displayed and a non-display area surrounding the display area, and the display panel has a plurality of the display areas. The condensing unit is arranged so that the first condensing region overlaps with both the display region and the non-display region, and the second condensing region overlaps with the non-display region. It may be configured.

According to the technique described in the present specification, it is possible to improve the brightness uniformity.

An exploded perspective view of the liquid crystal display device according to the first embodiment. Cross-sectional view of the backlight device constituting the liquid crystal display device cut along the Y-axis direction. Sectional view of the backlight device cut along the X-axis direction A perspective view of the light guide plate constituting the backlight device as viewed from the opposite plate surface side. Bottom view showing the configuration on the opposite plate surface of the light guide plate Top view showing LED, LED substrate and light guide plate constituting a backlight device Enlarged plan view of LED and light guide plate Cross-sectional view of the first condensing region of the first unit lens constituting the first lens portion cut along the X-axis direction. A cross-sectional view of the second condensing region of the first unit lens cut along the X-axis direction. Cross-sectional view of LED and light guide plate cut along the Y-axis direction Table showing the experimental results of Demonstration Example 1 of Demonstration Experiment 1 Table showing the experimental results of Demonstration Example 2 of Demonstration Experiment 1 Table showing the experimental results of Demonstration Example 3 of Demonstration Experiment 1 Table showing the experimental results of Demonstration Example 4 of Demonstration Experiment 1 Graph relating to brightness distribution in the X-axis direction in Demonstration Examples 1 to 4 of Demonstration Experiment 1 Top view of LED and light guide plate used in Comparative Experiment 1 A graph showing the relationship between the position and the Cm value in the Y-axis direction in Comparative Example 1 of Comparative Experiment 1. A graph showing the relationship between the position and the Cm value in the Y-axis direction in Comparative Example 2 of Comparative Experiment 1. A graph showing the relationship between the position and the Cm value in the Y-axis direction in Example 1 of Comparative Experiment 1. A table showing the experimental results of Comparative Examples 1 and 2 and Example 1 of Comparative Experiment 1. A table showing the experimental results of Comparative Examples 1 and 2 and Example 1 of Comparative Experiment 2. Cross-sectional view of the first condensing region of the first unit lens constituting the first lens portion of the light guide plate according to the second embodiment cut along the X-axis direction. A cross-sectional view of the second condensing region of the first unit lens cut along the X-axis direction. Top view of LED and light guide plate used in Comparative Experiment 3 Graph related to luminance distribution in the X-axis direction in Comparative Experiment 3 Graph showing the relationship between the apex angle and FWHM (full width at half maximum) in Comparative Experiment 3

<Embodiment 1>
The first embodiment will be described with reference to FIGS. 1 to 21. In this embodiment, a liquid crystal display device (display device) 10 is illustrated. The X-axis, Y-axis, and Z-axis are shown in a part of each drawing, and each axis direction is drawn so as to be the direction shown in each drawing. In the vertical direction, FIGS. 2, 3, 8, 9, and 10 are used as reference, and the upper side of the figure is the front side and the lower side of the figure is the back side.

As shown in FIG. 1, the liquid crystal display device 10 includes a liquid crystal panel (display panel) 11 for displaying an image and a back that is arranged on the back side of the liquid crystal panel 11 and irradiates the liquid crystal panel 11 with light used for display. A light device (lighting device) 12 is provided. The liquid crystal panel 11 has a rectangular plate shape as a whole, and its long side direction coincides with the X-axis direction, the short side direction coincides with the Y-axis direction, and the plate thickness direction coincides with the Z-axis direction. The liquid crystal panel 11 is formed by enclosing a liquid crystal layer between a pair of substrates, and of the pair of substrates, the one arranged on the front side is the CF substrate (opposing substrate), and the one arranged on the back side is the array substrate (the array substrate). TFT substrate). The CF substrate includes a color filter in which R (red), G (green), B (blue) and other colored portions are arranged in a predetermined arrangement, and a light-shielding portion (black matrix) that partitions between adjacent colored portions. , Is provided, and a structure such as an alignment film is provided. The array substrate (TFT substrate) is provided with structures such as a switching element (for example, TFT) connected to the source wiring and the gate wiring orthogonal to each other, a pixel electrode connected to the switching element, and an alignment film. .. The central portion of the liquid crystal panel 11 on the plate surface is a display area AA capable of displaying an image, and the frame-shaped outer peripheral end side portion surrounding the display area AA is a non-display area NAA. In FIG. 1 and the like, the outer shape of the display area AA is shown by a alternate long and short dash line. A reflective polarizing sheet 20 provided in the backlight device 12 described below is attached to a plate surface on the back side (outside) of the array substrate constituting the liquid crystal panel 11. The reflective polarizing sheet 20 will be described in detail later. A polarizing plate is attached to the front (outside) surface of the CF substrate constituting the liquid crystal panel 11.

Subsequently, the backlight device 12 will be described. As shown in FIG. 1, the backlight device 12 includes an LED (light source) 13, an LED substrate (light source substrate) 14 on which the LED 13 is mounted, a light guide plate 15 for guiding light from the LED 13, and a light guide plate 15. It is provided with at least a reflective sheet 16 arranged on the back side of the light source and a plurality of optical sheets 17 arranged so as to be interposed between the light source plate 15 and the liquid crystal panel 11. The backlight device 12 is a one-sided light input type edge light type in which the light of the LED 13 is input to the light guide plate 15 from only one side.

As shown in FIG. 1, the LED 13 has a configuration in which an LED chip is sealed with a sealing material on a substrate portion fixed to the LED substrate 14. In the LED 13, for example, the LED chip is assumed to emit blue light in a single color, and the phosphor is dispersed and blended in the encapsulant to emit white light as a whole. The phosphor includes a yellow phosphor, a green phosphor, a red phosphor and the like. The LED 13 is a so-called side light emitting type in which the surface adjacent to the mounting surface with respect to the LED substrate 14 is the light emitting surface 13A. The LED substrate 14 is installed with its plate surface parallel to the plate surface of the light guide plate 15, and the plate surface facing the back side is used as the mounting surface of the LED 13, and a plurality of LEDs 13 are X on the mounting surface. It is mounted so that it is lined up at intervals along the axial direction. The arrangement direction of the plurality of LEDs 13 coincides with the X-axis direction (second direction), and the X-axis direction is orthogonal to both the Y-axis direction and the Z-axis direction (the thickness direction of the light guide plate 15).

The light guide plate 15 is made of a synthetic resin material having a refractive index sufficiently higher than that of air and being substantially transparent (for example, an acrylic resin such as PMMA). As shown in FIG. 1, the light guide plate 15 has a plate shape, and the plate surface thereof is parallel to the plate surface of the liquid crystal panel 11. The light guide plate 15 has a long side direction on the plate surface that coincides with the X-axis direction, a short side direction that coincides with the Y-axis direction, and a plate thickness direction that is the normal direction of the plate surface coincides with the Z-axis direction. There is. The light guide plate 15 is arranged directly below the liquid crystal panel 11 and the optical sheet 17, and the end surface on the long side of one of the outer peripheral end surfaces thereof faces the light emitting surface 13A of the LED 13 and is from the light emitting surface 13A. It is assumed that the incoming light end face 15A into which light is incident. The incoming light end surface 15A has a horizontally long longitudinal shape with the X-axis direction, which is the arrangement direction of the LEDs 13, as the longitudinal direction. Of the pair of plate surfaces in the light guide plate 15, the front plate surface facing the liquid crystal panel 11 and the optical sheet 17 is the light emitting plate surface 15B that emits light that guides the inside, and faces the reflective sheet 16. The plate surface on the back side forming the shape is the opposite plate surface 15C. Then, the light guide plate 15 introduces the light emitted from the LED 13 toward the light guide plate 15 from the light incoming end surface 15A, propagates the light internally, and then propagates the light internally, and then the front side (light emitting side) along the Z-axis direction. It has a function to start up and emit light so that it faces toward. Further, the other end face on the long side side of the outer peripheral end face of the light guide plate 15, that is, the end face on the side opposite to the light entry end face 15A is referred to as the light entry opposite end face 15D. The normal direction of the incoming light end surface 15A (incoming light opposite end surface 15D) is the Y-axis direction (first direction), and the orthogonal direction along the light emitting plate surface 15A and orthogonal to the normal direction of the incoming light end surface 15B is X. It matches the axial direction. The normal direction of the incoming light end surface 15A is almost the same as the alignment direction of the LED 13 and the light guide plate 15 (the direction from the LED 13 to the light guide plate 15), and the optical axis of the LED 13 (the traveling direction of the light having the strongest emission intensity). Is almost the same as. The detailed structure of the light guide plate 15 will be described later.

As shown in FIG. 1, the reflective sheet 16 is arranged so that its plate surface is parallel to each plate surface of the liquid crystal panel 11 and the light guide plate 15 and covers the opposite plate surface 15C of the light guide plate 15. The reflective sheet 16 has excellent light reflectivity, and can efficiently raise the light leaking from the opposite plate surface 15C of the light guide plate 15 toward the front side, that is, the light emitting plate surface 15B. The reflective sheet 16 has an outer shape slightly larger than that of the light guide plate 15, and is arranged so as to be superimposed on the opposite plate surface 15C over almost the entire area.

As shown in FIG. 1, the optical sheet 17 has a sheet shape, and its plate surface is parallel to each plate surface of the liquid crystal panel 11 and the light guide plate 15. Similar to the liquid crystal panel 11 and the light guide plate 15, the optical sheet 17 has a plate surface in which the long side direction is the X-axis direction, the short side direction is the Y-axis direction, and the plate thickness direction, which is the normal direction of the plate surface, is Z. It matches the axial direction. The optical sheet 17 is arranged to be interposed between the liquid crystal panel 11 and the light guide plate 15 in the Z-axis direction, and emits light toward the liquid crystal panel 11 while imparting a predetermined optical action to the light emitted from the LED 13. It has a function such as making it. In the optical sheet 17, the back side, that is, the plate surface facing the light guide plate 15 side is the incoming light surface on which light is incident, whereas the front side, that is, the plate surface facing the liquid crystal panel 11 side is the plate surface facing the liquid crystal panel 11. It is considered to be the emitted light emitting surface. The optical sheet 17 includes a total of three sheets, which are the first prism sheet 18, the second prism sheet 19, and the reflective polarizing sheet 20 in this order from the back side.

First, the reflective polarizing sheet 20 will be described. The reflective polarizing sheet 20 has a polarizing layer having a specific polarizing axis (transmission axis), a multilayer film in which layers having different refractive indexes are alternately laminated, a protective layer, and the like. The polarizing layer is formed by mixing a polymer resin film such as a PVA (polyvinyl alcohol) film with an absorber such as iodine or a bicolor dye and uniaxially stretching the polarizing element to orient the absorber, and TAC (triacetyl). It is configured to be sandwiched by a protective film such as a cellulose) film. The polarization layer stretched uniaxially in this way has a polarization axis and an absorption axis orthogonal to the polarization axis, whereby linearly polarized light parallel to the polarization axis can be selectively transmitted. At the same time, circularly polarized light can be converted into linearly polarized light along the polarization axis. The polarization axis of this polarizing layer is orthogonal to the polarization axis of the polarizing plate attached to the outer plate surface of the CF substrate. In the multilayer film, a plurality of layers are made of, for example, PEN (polyethylene naphthalate), and the p-wave and s-wave contained in light exhibit different reflection characteristics (transmission characteristics) depending on the multilayer structure. That is, the multilayer film has a reflectance characteristic that the reflectance for s waves is generally higher than the reflectance for p waves. The s wave reflected by the multilayer film is reflected to the front side again by the light guide plate 15, the reflective sheet 16, another optical sheet 17, and the like, and at that time, it is separated into an s wave and a p wave. In this way, the reflective polarizing sheet 20 can be reused by reflecting the s wave originally absorbed by the polarizing layer to the back side by providing the multilayer film, and the light utilization efficiency (light utilization efficiency). As a result, the brightness) can be increased.

As shown in FIGS. 1 and 2, the first prism sheet 18 is provided on a sheet-shaped first base material 18A and a plate surface (light emitting side plate surface) on the front side (light emitting side) of the first base material 18A. It has one unit prism 18B and. The first base material 18A is made of a substantially transparent synthetic resin, and is specifically made of a crystalline transparent resin material such as PET (polyethylene terephthalate). The first base material 18A is formed into a sheet by stretching a crystalline transparent resin material as a raw material in a biaxial stretching process during production, which is suitable for reducing production costs. The first unit prism 18B is made of a substantially transparent ultraviolet curable resin material, which is a kind of photocurable resin material. In the production of the first prism sheet 18, for example, an uncured ultraviolet curable resin material is filled in a molding mold, and the first base material 18A is directed to the open end of the mold to uncured ultraviolet rays. When the curable resin material is arranged in contact with the front plate surface and the ultraviolet curable resin material is irradiated with ultraviolet rays through the first base material 18A in that state, the ultraviolet curable resin material is cured. The 1-unit prism 18B is integrally provided with the first base material 18A. The ultraviolet curable resin material constituting the first unit prism 18B is, for example, an acrylic resin such as PMMA. The refractive index of the ultraviolet curable resin material constituting the first unit prism 18B is preferably in the range of 1.49 to 1.52, and most preferably 1.49. The first unit prism 18B is provided so as to project from the plate surface of the first base material 18A toward the front side (the side opposite to the light guide plate 15 side) along the Z-axis direction. The first unit prism 18B has a cross-sectional shape cut along the Y-axis direction forming a substantially triangular shape (substantially chevron shape) and extends linearly along the X-axis direction (second direction). On the plate surface of the base material 18A, a plurality of them are continuously arranged side by side along the Y-axis direction (first direction) with almost no space between them. The first unit prism 18B has a base 18B1 parallel to the Y-axis direction (plate surface of the first base material 18A) and a pair of diagonal sides 18B2 and 18B3 rising from both ends of the bottom 18B1. Of the pair of hypotenuses 18B2 and 18B3 in the first unit prism 18B, the one on the LED13 side in the Y-axis direction is the first LED side hypotenuse (first light source side hypotenuse) 18B2, and the one on the opposite side is the hypotenuse on the opposite side of the first LED (first LED side hypotenuse). Hypotenuse on the opposite side of the first light source) 18B3. Of these, the light incident on the first unit prism 18B hits the oblique side 18B3 on the opposite side of the first LED and is refracted by the light traveling mainly in the direction away from the LED 13 in the Y-axis direction. On the other hand, the hypotenuse 18B2 on the first LED side is refracted by hitting the light incident on the first unit prism 18B, which travels mainly in the direction approaching the LED 13 in the Y-axis direction. In any case, most of the light refracted by the pair of hypotenuses 18B2 and 18B3 in the first unit prism 18B is selectively raised and focused in the Y-axis direction.

Then, as shown in FIGS. 1 and 2, the first unit prism 18B has an inclination angle (angle, front bottom angle) θ1 of the first LED side hypotenuse 18B2 with respect to the base 18B1 and an inclination angle 18B3 opposite to the first LED with respect to the base 18B1. When comparing the inclination angle (angle, bottom angle of the rear surface) θ2, the former is larger than the latter. That is, the first unit prism 18B has an asymmetric cross-sectional shape and is an isosceles triangle. Specifically, the inclination angle θ1 of the first LED side hypotenuse 18B2 with respect to the base 18B1 of the first unit prism 18B is preferably in the range of 50 ° to 60 °, and most preferably 55 °. On the other hand, the inclination angle θ2 of the hypotenuse 18B3 opposite to the first LED with respect to the base 18B1 of the first unit prism 18B is preferably in the range of 35 ° to 50 °, and most preferably 45 °. Further, the apex angle (angle) θ3 formed by the pair of hypotenuses 18B2 and 18B3 in the first unit prism 18B is preferably in the range of 70 ° to 95 °, and most preferably 80 °. The height dimension, the width dimension of the base 18B1, the inclination angle of each hypotenuse 18B2, 18B3 with respect to the base 18B1 and the like of the plurality of first unit prisms 18B arranged along the X-axis direction are all substantially the same. The arrangement intervals between the adjacent first unit prisms 18B are also substantially constant and are arranged at equal intervals.

As shown in FIGS. 1 and 2, the second prism sheet 19 is provided on the sheet-shaped second base material 19A and the front side (light emitting side) plate surface (light emitting side plate surface) of the second base material 19A. It has a 2-unit prism 19B and. The second base material 19A is made of a substantially transparent synthetic resin, and specifically, is made of a crystalline transparent resin material such as PET, which is the same as the first base material 18A. The second unit prism 19B is made of a substantially transparent ultraviolet curable resin material, which is a kind of photocurable resin material. The method for manufacturing the second prism sheet 19 is the same as the method for manufacturing the first prism sheet 18 described above. The ultraviolet curable resin material constituting the second unit prism 19B is, for example, an acrylic resin such as PMMA, and its refractive index is made higher than the refractive index of the material of the first unit prism 18B, for example, about 1.61. NS. The second unit prism 19B is provided so as to project from the plate surface of the second base material 19A toward the front side (the side opposite to the first prism sheet 18 side) along the Z-axis direction. The second unit prism 19B has a cross-sectional shape cut along the Y-axis direction in a substantially triangular shape (approximately a chevron shape) and extends linearly along the X-axis direction, and is a plate of the second base material 19A. A plurality of planes are arranged side by side continuously along the Y-axis direction with almost no space between them. The second unit prism 19B has a base 19B1 parallel to the Y-axis direction (plate surface of the second base material 19A) and a pair of diagonal sides 19B2 and 19B3 rising from both ends of the bottom 19B1. Of the pair of hypotenuses 19B2 and 19B3 in the second unit prism 19B, the one on the LED13 side in the Y-axis direction is the second LED side hypotenuse (second light source side hypotenuse) 19B2, and the one on the opposite side is the second LED opposite side hypotenuse ( The hypotenuse on the opposite side of the second light source) 19B3. Of the light incident on the second unit prism 19B, the light traveling in the direction away from the LED 13 mainly in the Y-axis direction hits the oblique side 19B3 on the opposite side of the second LED and is refracted. On the other hand, the second LED side hypotenuse 19B2 is refracted by hitting the light incident on the second unit prism 19B, which travels mainly in the direction approaching the LED 13 in the Y-axis direction. In any case, most of the light refracted by the pair of hypotenuses 19B2 and 19B3 in the second unit prism 19B is selectively raised and focused in the Y-axis direction.

Then, as shown in FIGS. 1 and 2, the second unit prism 19B has an inclination angle (angle, front bottom angle) θ4 of the second LED side hypotenuse 19B2 with respect to the base 19B1 and a second LED opposite hypotenuse 19B3 with respect to the base 19B1. The inclination angle (angle, bottom angle of the rear surface) θ5 is the same. That is, the second unit prism 19B has a symmetrical cross-sectional shape and is an isosceles triangle. Further, the inclination angle θ4 of the second LED side hypotenuse 19B2 with respect to the base 19B1 of the second unit prism 19B is the inclination angle θ1 of the first LED side hypotenuse 18B2 with respect to the base 18B1 of the first unit prism 18B provided on the first prism sheet 18. Has been made smaller than. Specifically, the inclination angles θ4 and θ5 of the pair of hypotenuses 19B2 and 19B3 with respect to the base 19B1 in the second unit prism 19B are preferably in the range of 40 ° to 50 °, and in particular, 45 °. Is the most preferable. On the other hand, in the second unit prism 19B, the apex angle (angle) θ6 formed by the pair of hypotenuses 19B2 and 19B3 is preferably in the range of 80 ° to 100 °, and in particular, 90 °, that is, a right angle. Is the most preferable. The height dimension, the width dimension of the base 19B1, the inclination angle of each hypotenuse 19B2, 19B3 with respect to the base 19B1 and the like of the plurality of second unit prisms 19B arranged along the X-axis direction are all substantially the same. The arrangement intervals between the adjacent second unit prisms 19B are also substantially constant and are arranged at equal intervals. Further, it is preferable that the height dimension and the arrangement interval in the second unit prism 19B are different from the height dimension and the arrangement interval in the first unit prism 18B in order to suppress the occurrence of interference fringes called moire.

Next, the detailed structure of the light guide plate 15 will be described. As shown in FIGS. 1 and 3, the light emitting plate surface 15B and the opposite plate surface 15C of the light guide plate 15 are provided with a first lens portion 21 and a second lens portion 22, respectively. The first lens unit 21 has a plurality of first unit lenses (condensing units) 21A extending along the Y-axis direction and lining up along the X-axis direction on the light emitting plate surface 15B of the light guide plate 15. In the present embodiment, the first lens unit 21 is a so-called lenticular lens, and the first unit lens 21A exclusively includes a convex cylindrical lens 25 projecting from the light emitting plate surface 15B to the front side. The cylindrical lens 25 included in the first unit lens 21A has a semicircular cross-sectional shape cut along the X-axis direction and a semi-circular shape extending linearly along the Y-axis direction, and has a peripheral surface thereof. Is in the shape of an arc. In order to integrally provide the first lens portion 21 having such a configuration on the light guide plate 15, for example, the light guide plate 15 is manufactured by injection molding, and the molding surface of the molding mold for molding the light emitting plate surface 15B is formed. A transfer shape for transferring the first lens portion 21 may be formed in advance. The detailed configuration of the first lens unit 21 will be described in detail later.

As shown in FIGS. 1 and 3, the second lens unit 22 is a plurality of second unit lenses extending along the Y-axis direction on the opposite plate surface 15C of the light guide plate 15 and lining up along the X-axis direction. It has (second condensing unit) 22A. In the present embodiment, the second lens unit 22 is a so-called prism type lens, and the second unit lens 22A exclusively includes a convex prism projecting from the light emitting plate surface 15B to the back side. The prism included in the second unit lens 22A has a substantially triangular (substantially chevron) cross-sectional shape cut along the X-axis direction and extends linearly along the Y-axis direction. The width dimension (dimension in the second direction) of the second unit lens 22A is constant over the entire length in the first direction. The second unit lens 22A has a cross-sectional shape of approximately an isosceles triangle, has a pair of slopes 22A1, and has an obtuse angle (an angle exceeding 90 °), specifically in the range of 100 ° to 150 °. The temperature is preferably 140 °. The plurality of second unit lenses 22A arranged along the X-axis direction have substantially the same apex angle, bottom surface width dimension (arrangement spacing), and height dimension. In the present embodiment, the arrangement interval (arrangement pitch) of the second unit lens 22A is larger than the arrangement interval of the first unit lens 21A. In order to integrally provide the second lens portion 22 having such a configuration on the light guide plate 15, for example, the light guide plate 15 is manufactured by injection molding, and the molding surface of the molding mold for molding the light emitting plate surface 15B is formed. A transfer shape for transferring the second lens portion 22 may be formed in advance.

According to such a configuration, as shown in FIG. 2, the light propagating in the light guide plate 15 is the first unit lens 21A constituting the first lens portion 21 on the light emitting plate surface 15B side in the Z-axis direction. By repeatedly reflecting the light on the arcuate peripheral surface, straightness is imparted so that the light travels substantially along the Y-axis direction. On the other hand, the light propagating in the light guide plate 15 hits the slope 22A1 of the second unit lens 22A constituting the second lens portion 22 on the opposite plate surface 15C side in the Z-axis direction and is repeatedly reflected, so that the light is generally reflected on the Y-axis. Straightness is given to travel along the direction. As a result, the light propagating in the light guide plate 15 is repeatedly along the Y-axis direction by the first unit lens 21A and the second unit lens 22A when going back and forth between the light emitting plate surface 15B and the opposite plate surface 15C. By imparting straightness to the lens, the efficiency of light utilization is improved and the brightness of the light emitted from the light emitting plate surface 15B is improved.

As shown in FIGS. 1 and 2, an idemitsu reflecting portion 23 is provided on the opposite plate surface 15C of the light guide plate 15. The Idemitsu reflecting unit 23 has a plurality of unit reflecting units 23A arranged at intervals along the Y-axis direction. The unit reflecting portion 23A is provided so as to project from the opposite plate surface 15C toward the back side along the Z-axis direction, and the cross-sectional shape cut along the Y-axis direction is a triangle. The unit reflecting unit 23A is a first reflecting surface 23A1 arranged on the LED13 side in the Y-axis direction and inclined with respect to the Y-axis direction, and a second reflecting surface 23A1 arranged on the opposite side and inclined with respect to the Y-axis direction. It has a reflecting surface 23A2. These reflecting surfaces 23A1, 23A2 reflect the light propagating in the light guide plate 15 and stand up toward the front side so as to have an angle close to the Z-axis direction to promote emission from the light emitting plate surface 15B. Is. The first reflecting surface 23A1 mainly functions to reflect and start up the light traveling away from the LED 13 in the Y-axis direction. On the other hand, the second reflecting surface 23A2 mainly functions to reflect and start up the light traveling so as to approach the LED 13 in the Y-axis direction. The first reflecting surface 23A1 has a gradient in which the distance from the light emitting plate surface 15B on which the light emitting reflecting portion 23 is not installed decreases as the distance from the LED 13 increases in the Y-axis direction. The inclination angle of the first reflecting surface 23A1 with respect to the Y-axis direction is, for example, about 8 °. The second reflecting surface 23A2 has a gradient in which the distance from the light emitting plate surface 15B on which the light emitting reflecting portion 23 is not installed increases as the distance from the LED 13 increases in the Y-axis direction, that is, a gradient opposite to that of the first reflecting surface 23A1. .. The inclination angle of the second reflection surface 23A2 with respect to the Y-axis direction is, for example, about 40 ° (the inclination angle with respect to the Z-axis direction is about 50 °), which is larger than the inclination angle of the first reflection surface 23A1. Further, the height dimension (dimension in the Z-axis direction) and the length dimension (dimension in the Y-axis direction) of the plurality of unit reflecting portions 23A arranged along the Y-axis direction increase as the distance from the LED 13 increases in the Y-axis direction. It is designed. More specifically, when the unit reflecting unit 23A closer to the LED 13 in the Y-axis direction and the unit reflecting unit 23A farther from the LED 13 in the Y-axis direction are compared, the latter is the first reflecting surface 23A1 and the second reflecting surface more than the former. Each area of 23A2 is large. As a result, on the side closer to the LED 13 in the Y-axis direction, it is difficult for light to hit the reflecting surfaces 23A1, 23A2 of the unit reflecting portion 23A and the light emission is suppressed, but on the side farther from the LED 13 in the Y-axis direction, the unit reflecting portion Light easily hits each of the reflecting surfaces 23A1, 23A2 of 23A, and light emission is promoted. As a result, the amount of light emitted from the light emitting plate surface 15B is made uniform on the LED13 side and the opposite side in the Y-axis direction.

As shown in FIGS. 1 and 2, the opposite plate surface 15C of the light guide plate 15 is provided with an inclined surface 24 arranged adjacent to the unit reflecting portion 23A in the Y-axis direction. A plurality of inclined surfaces 24 are arranged so as to be alternately and repeatedly arranged with the unit reflecting portion 23A in the Y-axis direction on the opposite plate surface 15C. The inclined surface 24 is connected to a second reflecting surface 23A2 in the unit reflecting portion 23A adjacent to the LED 13 side in the Y-axis direction and a first reflecting surface 23A1 in the unit reflecting portion 23A adjacent to the LED 13 side. ing. The inclined surface 24 has a gradient in which the distance from the light emitting plate surface 15B on which the light emitting light reflecting portion 23 is not installed increases as the distance from the LED 13 increases in the Y-axis direction. That is, the inclined surface 24 has the same inclination as the second reflecting surface 23A2 of the unit reflecting portion 23A. The inclined surface 24 has an inclined angle of, for example, about 1.4 ° with respect to the Y-axis direction, which is smaller than any of the inclined angles of the reflecting surfaces 23A1, 23A2 of the unit reflecting portion 23A. The inclined surface 24 having such a configuration reflects the light traveling in the light guide plate 15 so as to move away from the LED 13, thereby directing the light toward the light emitting plate surface 15B, but the angle of incidence of the light on the light emitting plate surface 15B. Does not exceed the critical angle, so the light is totally reflected by the light emitting plate surface 15B and guided to be farther from the LED 13. As a result, the emitted light from the light emitting plate surface 15B is less likely to be biased toward the LED 13 in the Y-axis direction. As described above, the light guide plate 15 is configured such that the inclination angle with respect to the Y-axis direction increases in the order of the inclined surface 24, the first reflecting surface 23A1, and the second reflecting surface 23A2. Further, the plurality of inclined surfaces 24 arranged along the Y-axis direction are designed so that the length dimension becomes smaller as the distance from the LED 13 increases in the Y-axis direction. This is because the length dimension of the unit reflection unit 23A increases as the distance from the LED 13 increases in the Y-axis direction, and the occupied range of the unit reflection unit 23A increases.

As shown in FIGS. 3 to 5, the light emitting light reflecting portion 23 and the inclined surface 24 having the above-described configuration are arranged so as to be sandwiched between two second unit lenses 22A adjacent to each other in the X-axis direction. Therefore, the light emitting light reflecting portion 23 and the inclined surface 24 are arranged so as to be alternately and repeatedly arranged with the second unit lens 22A in the X-axis direction. The maximum value of the protruding dimension (height dimension) from the opposite plate surface 15C of the unit reflecting portion 23A constituting the light emitting reflecting portion 23 is smaller than the protruding dimension of the second unit lens 22A. Therefore, even the unit reflecting portion 23A located on the farthest side from the LED 13 in the Y-axis direction does not protrude to the back side of the second unit lens 22A.

Here, the detailed configuration of the plurality of first unit lenses 21A constituting the first lens unit 21 will be described. As shown in FIG. 6, the plurality of first unit lenses 21A include two condensing regions A1 and A2 having different straightness imparted to the light propagating in the light guide plate 15. The two condensing regions A1 and A2 include a first condensing region A1 located on the side opposite to the LED13 side in the Y-axis direction (15D side opposite to the incoming light) and a Y-axis rather than the first condensing region A1. A second condensing region A2 located on the LED13 side (light entry end surface 15A side) in terms of direction is included. The plurality of first unit lenses 21A have relatively low straightness imparted to the light propagating in the light guide plate 15 in the first light collecting region A1, but in the second light collecting region A2, the inside of the light guide plate 15 is It is configured so that the straightness given to the propagating light is relatively high. In FIG. 6, the boundary line between the first condensing region A1 and the second condensing region A2 is illustrated by a linear alternate long and short dash line along the X-axis direction, and the outer shape of the display region AA is illustrated by a frame-shaped alternate long and short dash line. ing. Further, FIG. 6 schematically shows the arrangement pitch and the like of the first unit lens 21A.

According to such a configuration, on the side of the light guide plate 15 that is closer to the LED 13 in the Y-axis direction (light entry end surface 15A side), the light propagates in the light guide plate 15 by the second condensing region A2 of the first unit lens 21A. Since the straightness applied to the light is high, it is difficult for the light incident on the incoming light end surface 15A from the plurality of LEDs 13 to be diffused in the X-axis direction in the vicinity of the incoming light end surface 15A, and it is difficult for the light to overlap each other. As a result, bright bright areas (eyeball unevenness) are less likely to occur locally in the vicinity of the light incoming end surface 15A of the light emitting plate surface 15B of the light guide plate 15. On the other hand, on the side of the light guide plate 15 far from the LED 13 in the Y-axis direction (the end surface 15D opposite to the incoming light), the light propagating in the light guide plate 15 is imparted by the first condensing region A1 of the first unit lens 21A. Since the straightness is low, the light propagating in the light guide plate 15 is likely to be diffused in the X-axis direction. Therefore, even if the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A is uneven and the amount of light incident on the incoming light end surface 15A from the LED 13 far from the incoming light end surface 15A is small, the LED 13 close to the incoming light end surface 15A. Insufficient light amount is compensated for by diffusing light having a large amount of light incident on the incoming light end surface 15A in the first condensing region A1 in the X-axis direction. As a result, a band-shaped dark portion (straight-ahead unevenness) is less likely to occur in the vicinity of the LED 13 far from the light entry end surface 15A. As a result, the effect of improving the uniformity of the brightness of the light emitted from the light emitting plate surface 15B can be obtained, so that the light emitted from the backlight device 12 is less likely to have uneven brightness, and the liquid crystal panel 11 utilizes the emitted light. The display quality of the image displayed in is good.

Moreover, as shown in FIG. 6, the plurality of first unit lenses 21A are arranged so that the first condensing region A1 overlaps with both the display region AA and the non-display region NAA, and the second condensing region A2. Is configured to overlap the non-display area NAA. Here, there is a possibility that light may leak from the boundary portion between the first condensing region A1 and the second condensing region A2 in the plurality of first unit lenses 21A, and the leaked light enters the display region AA. , There is a possibility that it will be visually recognized as a bright line. In that respect, the boundary portion between the first condensing region A1 and the second condensing region A2 in the plurality of first unit lenses 21A is arranged so as to overlap with the non-display region NAA, and the display region AA is Since the arrangement is non-superimposed, even if light leaks from the boundary between the first condensing region A1 and the second condensing region A2, it is unlikely that the leaked light enters the display region AA. It has become. As a result, it is less likely that the display quality of the image displayed in the display area AA is deteriorated. Further, in the plurality of first unit lenses 21A, the distance from the boundary portion between the first condensing region A1 and the second condensing region A2 to the light entering end surface 15A of the light guide plate 15 is the light entering end surface 15A in the display region AA. It is made smaller than the distance from the side closest to the light entering end face 15A, for example, about half. Specifically, the distance from the boundary portion between the first condensing region A1 and the second condensing region A2 to the light entering end surface 15A of the light guide plate 15 is, for example, about 1.7 mm, whereas the display region. The distance from the side portion closest to the incoming light end surface 15A in AA to the incoming light end surface 15A is, for example, about 3.4 mm.

In the present embodiment, since the plurality of first unit lenses 21A are exclusively composed of the plurality of cylindrical lenses 25, the first condensing region A1 and the second condensing region A2 are configured as follows. .. That is, when the angle formed by the tangent line Ta at the base end of the arcuate peripheral surface of the cylindrical lens 25 with respect to the X-axis direction is defined as the "contact angle", the cylindrical lens 25 is shown in FIGS. 7 to 9. As shown, the contact angles θc1 and θc2 are different between the first condensing region A1 and the second condensing region A2. Here, the straightness imparted to the light by the cylindrical lens 25 varies depending on the magnitude of the contact angles θc1 and θc2, and the larger the contact angles θc1 and θc2, the higher the straightness imparted to the light tends to be. be. Since the plurality of cylindrical lenses 25 according to the present embodiment are configured such that the contact angle θc2 in the second condensing region A2 is larger than the contact angle θc1 in the first condensing region A1, the second condensing region A2 Then, the straightness imparted to the light is higher than that of the first condensing region A1. As a result, the light incident on the incoming light end surface 15A from the plurality of LEDs 13 is difficult to diffuse in the X-axis direction in the vicinity of the incoming light end surface 15A and is difficult to overlap with each other. Is less likely to occur. Since the plurality of cylindrical lenses 25 are configured such that the contact angle θc1 in the first condensing region A1 is smaller than the contact angle θc2 in the second condensing region A2, the second condensing region A1 is the second. The straightness imparted to the light is lower than that of the light condensing region A2. As a result, even if the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A is uneven and the amount of light incident on the incoming light end surface 15A from the LED 13 far from the incoming light end surface 15A is small, it is close to the incoming light end surface 15A. A large amount of light incident on the incoming light end surface 15A from the LED 13 diffuses in the first condensing region A1 in the X-axis direction to compensate for the lack of light amount, and a band-shaped dark portion is generated near the LED 13 far from the incoming light end surface 15A. It becomes difficult.

Specifically, as shown in FIGS. 7 and 8, the contact angle θc1 in the first condensing region A1 of the cylindrical lens 25 is in the range of 30 ° to 50 °, for example, about 49 °. When the contact angle θc1 in the first condensing region A1 is 30 ° or more, the straightness imparted to the light in the first condensing region A1 becomes sufficiently higher than when it is smaller than 30 °. Therefore, the brightness of the emitted light in the first condensing region A1 can be kept sufficiently high. If the contact angle θc1 in the first condensing region A1 is 50 ° or less, the straightness imparted to the light in the first condensing region A1 may be excessive as compared with the case where the contact angle θc1 is larger than 50 °. Since this can be avoided, even if the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A varies, it is possible to make it difficult for a band-shaped dark portion to be generated in the vicinity of the LED 13 far from the incoming light end surface 15A. On the other hand, as shown in FIGS. 7 and 9, the cylindrical lens 25 has a contact angle θc2 in the second condensing region A2 in the range of 55 ° to 70 °, for example, about 67 °. When the contact angle θc2 in the second condensing region A2 is 55 ° or more, the straightness imparted to the light in the second condensing region A2 becomes sufficiently higher than when it is smaller than 55 °. Therefore, it is possible to make it difficult to locally generate a bright bright portion in the vicinity of the light entering end surface 15A. If the contact angle θc2 in the second condensing region A2 is 70 ° or less, the straightness imparted to the light in the second condensing region A2 may be excessive as compared with the case where it is larger than 70 °. Since it can be avoided, it is possible to make it difficult to cause unevenness of light and darkness in which the arrangement of a plurality of LEDs 13 intermittently arranged along the X-axis direction is reflected in the vicinity of the light entry end surface 15A. The "unevenness of light and darkness" referred to here means that on the LED substrate 14, the area where the LED 13 is arranged and the area between the adjacent LEDs 13 where the LED 13 is not arranged are alternately arranged along the X-axis direction. As a result of the arrangement being reflected as the unevenness of the amount of incident light on the incoming light end surface 15A, it is visually recognized as the unevenness of the emitted light from the light emitting plate surface 15B in the vicinity of the incoming light end surface 15A.

As shown in FIGS. 7 to 9, the plurality of cylindrical lenses 25 have the same central position in the X-axis direction in the first condensing region A1 and the second condensing region A2, and the arrangement pitch in the X-axis direction. Are equal. That is, the cylindrical lens 25 has a configuration in which the first condensing region A1 and the second condensing region A2 are continuously connected without interruption in the middle. Along with this, the cylindrical lens 25 is assumed to continuously change the contact angle at the boundary portion between the first condensing region A1 and the second condensing region A2. Specifically, the arrangement pitch of the cylindrical lens 25 in the X-axis direction is constant at, for example, about 0.038 mm in both the first condensing region A1 and the second condensing region A2. According to such a configuration, as compared with the case where the above-mentioned arrangement pitch is different between the first condensing region and the second condensing region, the light incident on the incoming light end face 15A is from the second condensing region A2 side. It becomes difficult for the light to leak to the outside when traveling to the first light collecting region A1 side. As a result, the efficiency of light utilization is less likely to decrease, and the brightness is less likely to decrease. Further, in the cylindrical lens 25, the second condensing region A2 is larger than the first condensing region A1 in terms of height dimension (protruding height from the light emitting plate surface 15B), and the radius of curvature is the second. The second condensing region A2 is smaller than the first condensing region A1. Specifically, the cylindrical lens 25 has a height dimension of, for example, about 0.00845 mm and a radius of curvature of, for example, about 0.0248 mm in the first condensing region A1, whereas the second condensing region has a radius of curvature of about 0.0248 mm. In A2, the height dimension is, for example, about 0.01197 mm, and the radius of curvature is, for example, about 0.0199 mm.

As shown in FIG. 10, the light guide plate 15 includes a first light guide unit 26 in which the first condensing region A1 of the plurality of first unit lenses 21A (cylindrical lenses 25) is located, and a plurality of first unit lenses. It has a second light guide unit 27 in which the second light collecting region A2 of 21A is located. The first light guide unit 26 is arranged so that the formation range viewed in a plane coincides with the first condensing region A1 and overlaps with both the display region AA and the non-display region NAA of the liquid crystal panel 11. ing. The formation range of the second light guide unit 27 when viewed in a plane coincides with the second condensing region A2, and although it overlaps with the non-display region NAA of the liquid crystal panel 11, it does not overlap with the display region AA. It is arranged to be. The light guide plate 15 is configured such that the first light guide portion 26 and the second light guide portion 27 have different plate thicknesses (dimensions in the Z-axis direction), and the plate thickness of the second light guide portion 27 is different. However, it is made smaller than the plate thickness of the first light guide portion 26. An inclined surface 28 is formed on the light emitting plate surface 15B side at the boundary portion between the first light guide portion 26 and the second light guide portion 27 having different plate thicknesses. The inclined surface 28 prevents a steep step from being generated between the first light guide portion 26 and the second light guide portion 27, and suppresses the occurrence of light leakage. The difference in plate thickness between the first light guide unit 26 and the second light guide unit 27 is the height dimension in the first condensing region A1 and the height dimension in the second condensing region A2 in the first unit lens 21A. It is made larger than the difference with. Therefore, the first unit lens 21A is configured so that the second focusing region A2 is lower in the Z-axis direction than the first focusing region A1. Specifically, the difference in plate thickness between the first light guide unit 26 and the second light guide unit 27 is, for example, about 0.005 mm. As described above, since the plate thickness of the second light guide unit 27 is smaller than that of the first light guide unit 26, the light entering end surface 15A is larger than that in the case where the magnitude relation of the plate thickness is reversed. When the incident light travels from the second light guide unit 27 side to the first light guide unit 26 side in the Y-axis direction, it is difficult for the incident light to leak to the outside. As a result, the efficiency of light utilization is less likely to decrease, and the brightness is less likely to decrease. On the contrary, since the plate thickness of the first light guide unit 26 is larger than that of the second light guide unit 27, the light traveling in the first light guide unit 26 is likely to be diffused in the X-axis direction. Therefore, even if the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A is uneven and the amount of light incident on the incoming light end surface 15A from the LED 13 far from the incoming light end surface 15A is small, the LED 13 close to the incoming light end surface 15A By diffusing the light having a large amount of light incident on the incoming light end surface 15A in the X-axis direction in the first light guide unit 26, the lack of light amount can be easily compensated. As a result, a band-shaped dark portion is less likely to be generated in the vicinity of the LED 13 far from the light entering end surface 15A.

Next, in order to verify the superiority of the backlight device 12 and the liquid crystal display device 10 according to the present embodiment, the following demonstration experiments 1 and comparative experiments 1 and 2 were performed. First, the demonstration experiment 1 will be described. Demonstration experiment 1 relates to how the straightness imparted to the light propagating in the light guide plate by the cylindrical lens changes when the contact angle of the cylindrical lens formed on the light emitting plate surface of the light guide plate is changed. It is for obtaining knowledge. In this demonstration experiment 1, a light guide plate having the same configuration as that described before this paragraph is used except that the contact angle of the cylindrical lens is constant over the entire length. The light guide plate used in Demonstration Experiment 1 includes Demonstration Example 1 in which the contact angle of the cylindrical lens is 52 °, Demonstration Example 2 in which the contact angle of the cylindrical lens is 39 °, and the contact angle of the cylindrical lens is 28. Demonstration example 3 in which ° is set and Demonstration example 4 in which the contact angle of the cylindrical lens is 16 ° are included. Then, in the comparative experiment 1, the light from one LED arranged at the center position in the longitudinal direction (X-axis direction) of the light entering end surface with respect to the light entering end surface of the light guide plates according to the first to fourth demonstration examples is emitted. The brightness of the emitted light emitted from the light emitting plate surface in the incident state is measured, a diagram showing the brightness distribution on the light emitting plate surface by shading is created, and a graph related to the brightness distribution in the X-axis direction is created. bottom.

The experimental results of Demonstration Experiment 1 are as shown in FIGS. 11 to 15. FIG. 11 is a table showing the luminance distribution on the light emitting plate surface of Demonstration Example 1, FIG. 12 is a table showing the luminance distribution on the light emitting plate surface of Demonstration Example 2, and FIG. 13 is a table showing the luminance distribution on the light emitting plate surface of Demonstration Example 3. It is a table showing the brightness distribution on the surface, FIG. 14 is a table showing the brightness distribution on the light emitting plate surface of Demonstration Example 4, and FIG. 15 shows the luminance distribution in the X-axis direction in Demonstration Examples 1 to 4. It is a related graph. 11 to 15 show the contact angles of the cylindrical lens. In the figures relating to the brightness distribution on the light emitting plate surface shown in FIGS. 11 to 14, the high and low brightness is represented by the light and shade, and the higher the brightness, the lighter the brightness, and the lower the brightness, the darker the tendency. The unit of brightness shown on the vertical axis of the graph shown in FIG. 15 is “cd / m ² ”. The horizontal axis of the graph shown in FIG. 15 represents a position with the central position in the X-axis direction as a reference (0 mm), and the unit thereof is “mm”. Further, among the positive and negative symbols attached to the horizontal axis of the graph shown in FIG. 15, “− (minus)” indicates the luminance distribution shown in FIGS. 11 to 14 in the X-axis direction from the reference center position. Means the left side in, and "+ (plus)" means the right side in the same luminance distribution.

The experimental results of the demonstration experiment will be described. Comparing FIGS. 11 to 14, the larger the contact angle of the cylindrical lens, the higher the brightness range becomes elongated along the Y-axis direction and the larger the area, whereas the smaller the contact angle of the cylindrical lens, the higher the brightness range. It can be seen that the range of brightness expands in the X-axis direction and the area decreases. According to FIG. 15, as the contact angle of the cylindrical lens increases, the brightness at the central position in the X-axis direction tends to increase, and the brightness at a position separated from the central position in the X-axis direction by about 10 mm or more tends to decrease. You can see that it is in. On the contrary, as the contact angle of the cylindrical lens becomes smaller, the brightness at the central position in the X-axis direction tends to decrease, and the brightness tends to increase at a position about 10 mm or more away from the central position in the X-axis direction. I understand. The results of these experiments show that as the contact angle of the cylindrical lens increases, the efficiency with which light is repeatedly reflected by the arcuate peripheral surface improves, and the light travels more linearly along the Y-axis direction. On the contrary, when the contact angle of the cylindrical lens becomes small, the efficiency of repeated reflection of light by the arcuate peripheral surface decreases, so that the light becomes Y. It is presumed that this reflects the fact that it becomes difficult to travel linearly along the axial direction and it becomes easy to diffuse in the X-axis direction.

Next, comparative experiments 1 and 2 will be described. In Comparative Experiments 1 and 2, the light guide plate 15 described in the paragraph prior to Demonstration Experiment 1 was used as Example 1, and the light guide plate in which the contact angle of the cylindrical lens was constant over the entire length was used as Comparative Examples 1 and 2. There is. In Comparative Experiment 1, in Example 1 and Comparative Examples 1 and 2, the brightness distributions when the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface varies. In Comparative Experiment 2, in Example 1 and Comparative Examples 1 and 2, the brightness distributions when there is no variation in the arrangement of the plurality of LEDs 13 with respect to the incoming light end face are compared. Comparative Examples 1 and 2 use a light guide plate having the same configuration as that described in the paragraph prior to Demonstration Experiment 1 except that the contact angle of the cylindrical lens is constant over the entire length. .. The light guide plate of Comparative Example 1 has a contact angle of 49 ° in the cylindrical lens and is constant over the entire length. The light guide plate of Comparative Example 2 has a contact angle of 63 ° in the cylindrical lens and is constant over the entire length. In the light guide plate 15 of the first embodiment, the contact angle θc1 in the first condensing region A1 of the cylindrical lens 25 is 49 °, and the contact angle θc2 in the second condensing region A2 is 67 ° (FIG. 8). And see FIG. 9).

Comparative experiment 1 will be described in detail. As shown in FIG. 16, the comparative experiment 1 is performed after including a plurality of LEDs 13 arranged along the X-axis direction that are intentionally displaced in the Y-axis direction. Specifically, the plurality of LEDs 13 include a misaligned LED 13α that is misaligned so that the distance from the light entering end surface 15A in the Y-axis direction is about 0.1 mm larger than that of the other LEDs 13 every five counting from the end. It is arranged so that it can be used. In FIG. 16, the light input end surface 15A of the light guide plate 15 is shown by a chain double-dashed line. In the comparative experiment 1, all the LED 13 groups having such an arrangement are turned on, and the light is emitted from the light emitting plate surface in a state where the light is incident on the incoming light end faces of the light guide plates according to the first and second comparative examples. The brightness of the emitted light was measured, the Cm (Michelson Contrast) value was calculated based on the brightness, and the presence or absence of brightness unevenness was determined. The Cm value is obtained by subtracting the minimum brightness from the maximum brightness of the emitted light and dividing by the value obtained by adding the maximum brightness and the minimum brightness. When the Cm value is large, the difference between the maximum brightness and the minimum brightness is large and the sum of the maximum brightness and the minimum brightness is small, so that the brightness unevenness tends to be easily recognized. On the contrary, when the Cm value is small, the difference between the maximum brightness and the minimum brightness is small and the sum of the maximum brightness and the minimum brightness is large, so that the brightness unevenness tends to be difficult to be visually recognized. The inspector visually inspects the captured image to determine the presence or absence of uneven brightness.

The experimental results of Comparative Experiment 1 are as shown in FIGS. 17 to 20. 17 to 19 are graphs showing the relationship between the position and the Cm value in the Y-axis direction in Comparative Examples 1 and 2 and Example 1. As for the breakdown, FIG. 17 is a graph according to Comparative Example 1, FIG. 18 is a graph according to Comparative Example 2, and FIG. 19 is a graph according to Example 1. The horizontal axes of FIGS. 17 to 19 represent positions in the Y-axis direction with respect to the light input end surface of the light guide plate as a reference (0 mm), and the unit thereof is "mm". FIG. 20 is a table showing the contact angle, the average value of the Cm value, and the determination result of each cylindrical lens in Example 1 and Comparative Examples 1 and 2. In Example 1, since the contact angles θc1 and θc2 of the cylindrical lens 25 are different between the first condensing region A1 and the second condensing region A2, the respective numerical values are shown in FIG. On the other hand, in Comparative Examples 1 and 2, since the contact angles of the cylindrical lenses are constant, they are shown one by one in FIG. The average value of the Cm values shown in FIG. 20 is an average value calculated using each Cm value from 0 mm to 50 mm, which is a position in the Y-axis direction in the graphs shown in FIGS. 17 to 19. .. The determination result shown in FIG. 20 is "OK" when the luminance unevenness is generally not visible, and "impossible" when the luminance unevenness is visible.

The experimental results of Comparative Experiment 1 will be described. Comparing FIGS. 17 to 19, the Cm values of Comparative Example 1 (FIG. 17) and Example 1 (FIG. 19) are generally lower than those of Comparative Example 2 (FIG. 18), and in particular, Y. It can be seen that the Cm value is low when the position in the axial direction is around 10 mm. According to FIG. 20, in both Comparative Example 1 and Example 1, it was determined that the luminance unevenness was not visually recognized in the determination of the luminance unevenness, and the average value of the Cm values was lower than that of Comparative Example 2. .. On the other hand, in Comparative Example 2, it is determined that the luminance unevenness is visually recognized with respect to the determination of the luminance unevenness, and the average value of the Cm values is higher than that of Comparative Example 1 and Example 1. The results of these experiments are presumed to be due to the following reasons. That is, in Comparative Example 2, since the contact angle of the cylindrical lens is as large as 63 ° over the entire length, the light incident on the incoming light end face is given high straightness so as to travel along the Y-axis direction. It is difficult to diffuse in the axial direction. Therefore, even if the amount of light incident on the incoming light end face from the misaligned LED 13α arranged far from the incoming light end face is small, the amount of light incident on the incoming light end surface from the LED 13 arranged close to the incoming light end face is small. It is presumed that the light hardly diffuses to the side, and as a result, a band-shaped dark portion is formed in the vicinity of the misaligned LED 13α far from the light entry end face. On the other hand, in Comparative Example 1, since the contact angle of the cylindrical lens is as small as 49 ° over the entire length, the light incident on the incoming light end face is given straightness so as to travel along the Y-axis direction. The straightness provided is lower than that of Comparative Example 2, and it is easy to diffuse in the X-axis direction. As a result, when the amount of light incident on the incoming light end face from the misaligned LED 13α arranged far from the incoming light end face is small, the amount of light incident on the incoming light end face from the LED 13 arranged close to the incoming light end face is small. It is presumed that the light is easily diffused to the side, and as a result, a band-shaped dark portion is less likely to be generated in the vicinity of the misaligned LED 13α far from the light entry end face. In Example 1, the contact angle θc1 of the first condensing region A1 of the cylindrical lens 25 is 49 °, which is the same value as the contact angle of the cylindrical lens in Comparative Example 1, so that the light entering end surface The straightness imparted to the light incident on the lens is lower than that of Comparative Example 2 and is equivalent to that of Comparative Example 1. Therefore, when the amount of light incident on the incoming light end surface 15A from the misaligned LED 13α arranged far from the incoming light end surface 15A is small, the amount of light incident on the incoming light end surface 15A from the LED 13 arranged close to the incoming light end surface 15A is large. However, it is presumed that the light is easily diffused to the less side, and as a result, a band-shaped dark portion is less likely to be generated in the vicinity of the misaligned LED 13α far from the light entering end surface 15A.

Comparative experiment 2 will be described in detail. In the comparative experiment 2, all of the plurality of LED 13 groups arranged in an arrangement with no variation in the arrangement with respect to the incoming light end face are turned on, and light is incident on the incoming light end faces of the light guide plates according to Example 1 and Comparative Examples 1 and 2. An image is taken from the front side (light emitting plate surface side) in this state, the presence or absence of brightness unevenness is determined based on the image, and the brightness related to the emitted light emitted from the light emitting plate surface is measured, and the brightness is determined. The Cm value was calculated based on this. As in Comparative Experiment 1, the inspector visually inspects the captured image to determine the presence or absence of luminance unevenness. The Cm value is as described in Comparative Experiment 1. The experimental results of Comparative Experiment 2 are as shown in FIG. FIG. 21 is a table showing the contact angle of each cylindrical lens, the captured image, the maximum value of the Cm value, and the determination result in Example 1 and Comparative Examples 1 and 2. The description regarding the contact angle in FIG. 21 is the same as that in FIG. 20 of Comparative Experiment 1. The maximum value of the Cm value shown in FIG. 21 is the maximum value when a plurality of Cm values from the light input end surface of the light guide plate to a distance of 20 mm in the Y-axis direction are calculated. That is, it can be said that the maximum value of this Cm value represents the degree of the least favorable brightness unevenness assumed in the vicinity of the light input end surface of the light guide plate. The determination result shown in FIG. 21 is "good" when the luminance unevenness is not visually recognized, and "impossible" when the luminance unevenness is visually recognized. Of these, the "good" determination result means a better state than the "OK" determination result shown in FIG.

The experimental results of Comparative Experiment 2 will be described. According to FIG. 21, in both Comparative Example 2 and Example 1, it was determined that the luminance unevenness was not visually recognized in the determination of the luminance unevenness, and the maximum value of the Cm value was lower than that of Comparative Example 1. On the other hand, in Comparative Example 1, it is determined that the luminance unevenness is visually recognized with respect to the determination of the luminance unevenness, and the maximum value of the Cm value is higher than that of Comparative Example 2 and Example 1. The results of these experiments are presumed to be due to the following reasons. That is, in Comparative Example 1, since the contact angle of the cylindrical lens is as small as 49 ° over the entire length, the light incident on the incoming light end face is imparted with straightness so as to travel along the Y-axis direction. The straightness applied is lower than that of 2, and the light is easily diffused in the X-axis direction. Therefore, the light incident on the incoming light end faces from the plurality of LEDs diffuses in the vicinity of the incoming light end faces in the X-axis direction and overlaps with each other. As a result, it is presumed that a bright portion where the amount of light emitted locally increases in the portion between the LEDs in the X-axis direction is likely to occur in the vicinity of the light entry end face. On the other hand, in Comparative Example 2, since the contact angle of the cylindrical lens is as large as 63 ° over the entire length, the light incident on the incoming light end face is given high straightness so as to travel along the Y-axis direction. , Light is hard to diffuse in the X-axis direction. As a result, the light incident on the incoming light end faces from the plurality of LEDs is difficult to diffuse in the X-axis direction in the vicinity of the incoming light end faces, and it is difficult for them to overlap each other. As a result, it is presumed that it is difficult for bright bright areas to be locally generated near the end face of the incoming light. In Example 1, the contact angle θc1 of the second condensing region A2 of the cylindrical lens 25 is 67 °, which is larger than the contact angle of the cylindrical lens in Comparative Example 2, so that the light entering end surface The straightness imparted to the light incident on the lens is higher than that of any of Comparative Examples 1 and 2, and the light is less likely to be diffused in the X-axis direction. Therefore, in the vicinity of the incoming light end surface 15A, the second condensing region A2 of the cylindrical lens 25 imparts higher straightness to the light, making it more difficult to diffuse in the X-axis direction and making it difficult for them to overlap each other. .. As a result, it is presumed that locally bright bright areas are less likely to occur in the vicinity of the light entry end surface 15A.

As described above, the backlight device (illumination device) 12 of the present embodiment has a plate shape, and at least a part of the outer peripheral end surface is an incoming light end surface 15A, and one plate surface emits light. A light guide plate 15 which is a light emitting plate surface 15B to emit light, a plurality of LEDs (light sources) 13 arranged along an incoming light end surface 15A, and an opposite plate which is a plate surface on the light guide plate 15 opposite to the light emitting plate surface 15B. It is a first unit lens (condensing part) 21A provided on one of the surface 15C and the light emitting plate surface 15B, and extends along the first direction along the normal direction of the light entering end surface 15A. A first, in which a plurality of LEDs are arranged side by side along a second direction along the arrangement direction of the plurality of LEDs 13 and give straightness to the light propagating in the light guide plate 15 so as to travel along the first direction. The unit lens 21A is provided, and the plurality of first unit lenses 21A are arranged on the LED13 side in the first direction with respect to the first condensing region A1 and the first condensing region A1 and are the first with respect to light. A second condensing region A2, which imparts higher straightness than the first condensing region A1, is included.

In this way, the light emitted from the plurality of LEDs 13 and incident on the light entering end surface 15A of the light guide plate 15 propagates in the light guide plate 15 and then is emitted from the light emitting plate surface 15B. Since a plurality of first unit lenses 21A are provided on one of the opposite plate surface 15C and the light emitting plate surface 15B of the light guide plate 15, a plurality of first units of light propagating in the light guide plate 15 are provided. The unit lens 21A imparts straightness so as to travel along the first direction. Therefore, as compared with the case where the light is diffused in the second direction as in the conventional case, it is suitable for improving the light utilization efficiency and the brightness.

The plurality of first unit lenses 21A have different linearity imparted to the light in the first condensing region A1 and the second condensing region A2, so that the following actions and effects can be obtained. .. That is, in the second condensing region A2 arranged on the LED13 side of the first condensing region A1 in the first direction, the straightness imparted to the light by the plurality of first unit lenses 21A is the first condensing region A1. Since it is considered to be higher than the above, the light incident on the incoming light end surface 15A from the plurality of LEDs 13 is diffused in the second direction on the side of the light guide plate 15 close to the LED 13 (near the incoming light end surface 15A) in the first direction. It becomes difficult to do so and it becomes difficult to overlap each other. As a result, it becomes difficult for a bright bright portion to be locally generated in the vicinity of the light incoming end surface 15A of the light emitting plate surface 15B of the light guide plate 15. On the other hand, in the first condensing region A1 arranged on the side opposite to the LED13 side of the second condensing region A2 in the first direction, the straightness imparted to the light by the plurality of first unit lenses 21A is obtained. Since the light is lower than the second condensing region A2, the light propagating in the light guide plate 15 is likely to be diffused in the second direction in the first condensing region A1. Therefore, even if the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A is uneven and the amount of light incident on the incoming light end surface 15A from the LED 13 far from the incoming light end surface 15A is small, the LED 13 close to the incoming light end surface 15A The lack of light amount is compensated for by diffusing the light having a large amount of light incident on the incoming light end surface 15A in the second direction in the first condensing region A1. As a result, a band-shaped dark portion is less likely to be generated in the vicinity of the LED 13 far from the light entry end surface 15A. As a result, the uniformity of the brightness of the light emitted from the light emitting plate surface 15B is improved.

Further, the plurality of first unit lenses 21A include a plurality of cylindrical lenses 25 having an arcuate peripheral surface, and the plurality of cylindrical lenses 25 have a tangent Ta at the proximal end portion of the peripheral surface. With respect to the contact angles θc1 and θc2, which are angles formed in the two directions, the second condensing region A2 is configured to be larger than the first condensing region A1. The straightness imparted to the light by the cylindrical lens 25 varies according to the contact angles θc1 and θc2, which are the angles formed by the tangent Ta at the proximal end of the peripheral surface of the cylindrical lens 25 with respect to the second direction, and makes contact. The larger the angles θc1 and θc2, the higher the straightness given to the light tends to be. Since the plurality of cylindrical lenses 25 are configured such that the second condensing region A2 is larger than the first condensing region A1 with respect to the contact angles θc1 and θc2, the first collection in the second condensing region A2. The straightness imparted to the light is higher than that in the light region A1, and it is difficult for a bright bright portion to be locally generated in the vicinity of the light entering end surface 15A. Since the plurality of cylindrical lenses 25 are configured such that the first condensing region A1 is smaller than the second condensing region A2 with respect to the contact angles θc1 and θc2, the second condensing region A1 is the second collection. The straightness imparted to the light is lower than that of the light region A2, and even when the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A varies, a band-shaped dark portion is less likely to occur in the vicinity of the LED 13 far from the incoming light end surface 15A.

Further, in the plurality of cylindrical lenses 25, the contact angle θc1 in the first condensing region A1 is in the range of 30 ° to 50 °, whereas the contact angle θc2 in the second condensing region A2 is 55 ° to 70. It is in the range of °. If the contact angle of the cylindrical lens in the first condensing region is smaller than 30 °, the straightness imparted to the light in the first condensing region A1 becomes insufficient, so that the brightness may decrease. Further, if the contact angle of the cylindrical lens in the first condensing region is larger than 50 °, the straightness imparted to the light in the first condensing region A1 becomes excessive, so that a plurality of light entering end faces 15A are provided. When the arrangement of the LEDs 13 varies, a band-shaped dark portion may easily occur in the vicinity of the LED 13 far from the light entering end surface 15A. In that respect, the contact angles θc1 of the plurality of cylindrical lenses 25 in the first condensing region A1 are set in the range of 30 ° to 50 °, so that the brightness of the emitted light in the first condensing region A1 is kept sufficiently high. In addition, even if the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A is uneven, it is possible to make it difficult for a band-shaped dark portion to be formed in the vicinity of the LED 13 far from the incoming light end surface 15A. On the other hand, if the contact angle θc2 of the cylindrical lens 25 in the second condensing region A2 is smaller than 55 °, the straightness imparted to the light in the second condensing region A2 becomes insufficient, so that the vicinity of the incoming light end surface 15A There is a risk that bright bright areas are likely to occur locally. Further, if the contact angle of the cylindrical lens in the second condensing region is larger than 70 °, the straightness imparted to the light in the second condensing region A2 becomes excessive, so that there are a plurality of light incident surfaces in the vicinity of the end face 15A. There is a possibility that unevenness of light and darkness reflecting the arrangement of the LEDs 13 of the above is likely to occur. In that respect, the contact angles θc2 of the plurality of cylindrical lenses 25 in the second condensing region A2 are set in the range of 55 ° to 70 °, so that it is difficult to locally generate a bright bright portion in the vicinity of the light entering end surface 15A. At the same time, it is possible to reduce the unevenness of light and darkness.

Further, the plurality of first unit lenses 21A exclusively include a plurality of cylindrical lenses 25. In this way, it becomes easier to design and manufacture the molding die required for manufacturing the light guide plate 15 as compared with the case where the plurality of first unit lenses include those other than the cylindrical lens 25. ..

Further, the light guide plate 15 includes a first light guide unit 26 in which the first light collection region A1 of the plurality of first unit lenses 21A is located, and a second light collection region A2 of the plurality of first unit lenses 21A. The second light guide unit 27 has a second light guide unit 27 in which the light guide unit 27 is located, and the plate thickness of the second light guide unit 27 is smaller than that of the first light guide unit 26. In this way, the second light guide unit 27 in which the second condensing region A2 in the plurality of first unit lenses 21A is located is the first in which the first condensing region A1 in the plurality of first unit lenses 21A is located. Since it is arranged on the light entering end surface 15A side in the first direction from the light guide portion 26 and its plate thickness is smaller than that of the first light guide portion 26, if the magnitude relationship of the plate thickness is reversed. Compared with the above, when the light incident on the incoming light end surface 15A travels from the second light guide unit 27 side to the first light guide unit 26 side in the first direction, it is less likely to leak to the outside. As a result, the efficiency of light utilization is less likely to decrease, and the brightness is less likely to decrease. Further, since the plate thickness of the first light guide unit 26 is larger than that of the second light guide unit 27, the light traveling in the first light guide unit 26 is likely to be diffused in the second direction. Therefore, even if the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A is uneven and the amount of light incident on the incoming light end surface 15A from the LED 13 far from the incoming light end surface 15A is small, the LED 13 close to the incoming light end surface 15A Since the light having a large amount of light incident on the incoming light end surface 15A is diffused in the second direction in the first light guide unit 26, the lack of light amount is easily compensated for, and a band-shaped dark portion is formed near the LED 13 far from the incoming light end surface 15A. It becomes difficult to occur.

Further, the plurality of first unit lenses 21A have the same arrangement pitch in the second direction in the first condensing region A1 and the second condensing region A2. In this way, as compared with the case where the arrangement pitches are different as described above, the light incident on the incoming light end surface 15A leaks to the outside when traveling from the second condensing region A2 side to the first condensing region A1 side. It becomes difficult to put out. As a result, the efficiency of light utilization is less likely to decrease, and the brightness is less likely to decrease.

Further, the second unit lens (second condensing portion) 22A provided on the other side of the opposite plate surface 15C and the light emitting plate surface 15B of the light guide plate 15 extends along the first direction. A second unit lens 22A is provided, which is arranged side by side along the second direction and imparts straightness to the light propagating in the light guide plate 15 so as to travel along the first direction. In this way, the light propagating in the light guide plate 15 travels along the first direction by the plurality of first unit lenses 21A when reaching one of the opposite plate surface 15C and the light emitting plate surface 15B. The straightness is imparted, and when the other of the opposite plate surface 15C and the light emitting plate surface 15B is reached, the straightness is imparted so as to travel along the first direction by the plurality of second unit lenses 22A. .. In this way, when light travels back and forth between the opposite plate surface 15C and the light emitting plate surface 15B, the first unit lens 21A and the second unit lens 22A repeatedly impart straightness, thereby achieving light utilization efficiency and It is suitable for further improving the brightness. On the other hand, when the arrangement of the plurality of LEDs 13 with respect to the incoming light end surface 15A is uneven and the amount of light incident on the incoming light end surface 15A from the LED 13 far from the incoming light end surface 15A is small, the light entering end surface 15A is used. There is a concern that a band-shaped dark portion is more likely to occur in the vicinity of the distant LED 13. In that respect, the straightness imparted to the light in the first condensing region A1 by the plurality of first unit lenses 21A is lower than that in the second condensing region A2, so that in the first condensing region A1. Since the light is easily diffused in the second direction, even if the light is imparted with straightness by the second unit lens 22A, a band-shaped dark portion is less likely to be generated in the vicinity of the LED 13 far from the light entry end surface 15A.

Further, the light emitting reflecting portion 23 provided on the other side of the opposite plate surface 15C and the light emitting plate surface 15B of the light guide plate 15 is arranged at intervals along the first direction to reflect light and emit light. The light emitting reflecting unit 23 including a plurality of unit reflecting units 23A emitted from the light plate surface 15B is provided. In this way, the light propagating in the light guide plate 15 is reflected by a plurality of unit reflecting units 23A arranged at intervals along the first direction on the way, so that the light is emitted from the light emitting plate surface 15B. Prompted.

Further, of the opposite plate surface 15C and the light emitting plate surface 15B of the light guide plate 15, the plate surface on which the light emitting reflecting portion 23 is arranged is arranged adjacent to the unit reflecting portion 23A in the first direction and moves away from the LED 13. An inclined surface 24 having a slope that increases the distance from the plate surface on which the light emitting light reflecting unit 23 is not installed is provided. In the light emitting light reflecting unit 23, the unit reflecting unit 23A is arranged on the LED13 side in the first direction. The light guide plate 15 has a first reflecting surface 23A1 that is inclined with respect to the first direction and a second reflecting surface 23A2 that is arranged on the opposite side thereof and is inclined with respect to the first direction. The inclination angle with respect to the first direction is configured to increase in the order of the inclined surface 24, the first reflecting surface 23A1, and the second reflecting surface 23A2. In this way, the light traveling in the light guide plate 15 so as to move away from the LED 13 in the first direction has a gradient in which the distance from the plate surface on which the light emission reflecting portion 23 is not installed increases as the distance from the LED 13 increases on the way. Reflected by the surface 24, it is guided away from the LED 13 in the first direction. As a result, the emitted light from the light emitting plate surface 15B is less likely to be biased toward the LED 13 in the first direction. Since the inclination angle of the inclined surface 24 with respect to the first direction is smaller than that of any of the reflecting surfaces of the unit reflecting portion 23A, the reflected light can be guided to a side farther from the LED 13.

Of the light propagating in the light guide plate 15, the light traveling away from the LED 13 in the first direction is reflected by the first reflecting surface 23A1 of the unit reflecting unit 23A to promote light emission. On the other hand, among the light propagating in the light guide plate 15, the light traveling toward the LED 13 in the first direction is less than the light traveling away from the LED 13 in the first direction, but the light traveling away from the LED 13 is the first of the unit reflecting unit 23A. 2 Reflected by the reflecting surface 23A2 to promote light output. Since the inclination angle of the first reflecting surface 23A1 with respect to the first direction is smaller than that of the second reflecting surface 23A2, the rising action acting on the reflected light is weaker than that of the second reflecting surface 23A2. Therefore, even if more light travels away from the LED 13 in the first direction than in the opposite direction, it is possible to avoid excessive light emission. On the other hand, since the second reflecting surface 23A2 has a larger inclination angle with respect to the first direction than the first reflecting surface 23A1, the rising action acting on the reflected light is stronger than that of the first reflecting surface 23A1. Therefore, even if the amount of light traveling toward the LED 13 in the first direction is less than that in the opposite direction, the light can be fully emitted, and the light utilization efficiency is improved.

Further, the liquid crystal display device (display device) 10 according to the present embodiment includes the backlight device 12 described above and a liquid crystal panel (display panel) 11 that displays using the light from the backlight device 12. Be prepared. According to the liquid crystal display device 10 having such a configuration, since the uniformity of the brightness related to the emitted light of the backlight device 12 is improved, it is possible to realize a display having excellent display quality.

Further, the liquid crystal panel 11 has a display area AA on which an image is displayed and a non-display area NAA surrounding the display area AA, and the plurality of first unit lenses 21A have a first condensing area A1. The second condensing region A2 is arranged so as to overlap with both the display area AA and the non-display area NAA. In this way, an image is displayed in the display area AA of the liquid crystal panel 11 by using the light emitted from the backlight device 12. Since the plurality of first unit lenses 21A are arranged so that the boundary portion between the first condensing region A1 and the second condensing region A2 overlaps with the non-display region NAA, light is tentatively emitted from the above-mentioned boundary portion. Even if a leak occurs, it is unlikely that the leaked light will deteriorate the display quality of the image displayed in the display area AA.

<Embodiment 2>
The second embodiment will be described with reference to FIGS. 22 to 26. In the second embodiment, the configuration of the first unit lens 121A is changed. It should be noted that duplicate description of the same structure, action and effect as in the first embodiment will be omitted.

As shown in FIGS. 22 and 23, the plurality of first unit lenses 121A constituting the first lens unit 121 provided on the light guide plate 115 according to the present embodiment includes a plurality of composite lenses in addition to the plurality of cylindrical lenses 125. The lens 29 is included. Although the composite lens 29 is common to the cylindrical lens 125 in that it extends along the Y-axis direction and a plurality of the composite lenses are arranged side by side along the X-axis direction, a part of the peripheral surface is linear. It differs in that it is. Specifically, the composite lens 29 has an arcuate peripheral surface similar to that of the cylindrical lens 125 in the first condensing region A1, but has a pair of hypotenuses 29B sandwiching the apex 29A and the apex 29A in the second condensing region A2. Has a peripheral surface that includes. The composite lens 29 has a semicircular cross-sectional shape cut along the X-axis direction in the first condensing region A1 and has a semi-circular shape extending linearly along the Y-axis direction. In the second condensing region A2, the composite lens 29 has a substantially triangular (substantially chevron) cross-sectional shape cut along the X-axis direction and a prism shape extending linearly along the Y-axis direction. The shape of the composite lens 29 is assumed to change continuously at the boundary between the first condensing region A1 and the second condensing region A2. According to the composite lens 29 having such a configuration, in the second condensing region A2, the light is repeatedly totally reflected by the pair of hypotenuses 29B sandwiching the top 29A, so that the light travels straight along the Y-axis direction. Can be granted. Therefore, the composite lens 29 can impart higher straightness to the light in the second condensing region A2 as compared with the cylindrical lens 125, so that the light incident on the incoming light end surface 115A from the plurality of LEDs 113 can be applied. In the vicinity of the incoming light end surface 115A, it becomes difficult to diffuse in the X-axis direction, and it becomes difficult for them to overlap each other. As a result, it is possible to make it more difficult for a locally bright bright portion to be generated in the second condensing region A2. On the other hand, since the composite lens 29 has an arcuate peripheral surface in the first condensing region A1, the straightness imparted to the light in the first condensing region A1 is similar to that of the cylindrical lens 125. It has become. The composite lens 29 having such a configuration is arranged so as to be adjacent to the cylindrical lens 125 in the X-axis direction. That is, the plurality of first unit lenses 121A are configured such that the cylindrical lens 125 and the composite lens 29 are arranged so as to be alternately and repeatedly arranged one by one in the X-axis direction. In this way, the cylindrical lens 125 and the composite lens 29, which are arranged so as to be arranged alternately and repeatedly, impart different straightness to the light in the second condensing region A2, so that the light is locally arranged in the vicinity of the incoming light end surface 115A. It is possible to make bright bright areas less likely to occur. The number of installations of the cylindrical lens 125 and the compound lens 29 is almost the same.

Numerical values relating to the cylindrical lens 125 and the composite lens 29 will be described. As shown in FIGS. 22 and 23, the cylindrical lens 125 has a contact angle θc3 in the first condensing region A1 in the range of 30 ° to 50 °, for example, about 48 °, whereas the second condensing region A1 has a contact angle of about 48 °. The contact angle θc4 in the condensing region A2 is in the range of 55 ° to 70 °, and is, for example, about 67 °. The cylindrical lens 125 has a height dimension of, for example, about 0.00914 mm and a radius of curvature of about 0.027 mm in the first condensing region A1, whereas the height of the cylindrical lens 125 is, for example, about 0.027 mm in the second condensing region A2. The dimension is, for example, about 0.017 mm, and the radius of curvature is, for example, about 0.027 mm. That is, the cylindrical lens 125 has the same radius of curvature, although the height dimension is different between the first condensing region A1 and the second condensing region A2. The arrangement pitch of the cylindrical lens 125 in the X-axis direction is constant at, for example, about 0.082 mm in both the first condensing region A1 and the second condensing region A2.

On the other hand, as shown in FIGS. 22 and 23, the composite lens 29 has a contact angle θc5 in the range of 30 ° to 50 ° in the first condensing region A1 having the same shape as the cylindrical lens 125. For example, it is about 48 °. That is, the cylindrical lens 125 and the composite lens 29 have the same contact angles θc3 and θc5 in the first condensing region A1. In this way, the straightness imparted to the light by the cylindrical lens 125 and the composite lens 29 in the first condensing region A1 becomes equivalent. As a result, even when the arrangement of the plurality of LEDs 113 with respect to the light entering end surface 115A is uneven, it is possible to make it more difficult for a band-shaped dark portion to be generated in the vicinity of the LED 113 far from the light entering end surface 115A. The composite lens 29 has a height dimension of, for example, about 0.00914 mm and a radius of curvature of, for example, about 0.027 mm in the first condensing region A1. That is, the composite lens 29 has substantially the same shape as the cylindrical lens 125 in the first condensing region A1. The height dimension of the composite lens 29 in the second condensing region A2 is, for example, about 0.017 mm, and the apex angle θ7, which is the angle formed by the pair of hypotenuses 29B, is in the range of 80 ° to 100 °. For example, it is about 90 °. Here, if the angle formed by the pair of hypotenuses in the composite lens is larger than 100 °, depending on the setting of the contact angle θc4 in the second condensing region A2 of the cylindrical lens 125, the composite lens may generate light. The straightness imparted may be lower than the straightness imparted to the light by the cylindrical lens 125. In that respect, if the apex angle θ7 in the second condensing region A2 of the composite lens 29 is 100 ° or less as described above, the contact angle θc4 in the second condensing region A2 of the cylindrical lens 125 is set. Instead, the straightness imparted to the light by the composite lens 29 in the second condensing region A2 is higher than the straightness imparted to the light by the cylindrical lens 125. As a result, it is possible to make it more difficult for a bright bright portion to be locally generated in the vicinity of the light entering end surface 115A. On the other hand, if the apex angle in the second condensing region of the composite lens is smaller than 80 °, the shape reproducibility of the vicinity of the apex of the second condensing region in the composite lens will be improved when the light guide plate is manufactured by injection molding. It tends to be low and difficult to manufacture the light guide plate. In that respect, if the apex angle θ7 in the second condensing region A2 of the composite lens 29 is 80 ° or more, when the light guide plate 115 is manufactured by injection molding, the second condensing region A2 in the composite lens 29 The shape reproducibility near the top 29A is kept sufficiently high, whereby the light guide plate 115 can be easily manufactured. The arrangement pitch of the composite lens 29 in the X-axis direction is constant at, for example, about 0.082 mm in both the first condensing region A1 and the second condensing region A2. That is, the cylindrical lens 125 and the composite lens 29 have the same arrangement pitch in the X-axis direction. Therefore, the arrangement pitch of the cylindrical lens 125 and the composite lens 29 in the X-axis direction is constant at, for example, about 0.041 mm in both the first condensing region A1 and the second condensing region A2. In the present embodiment, the difference in plate thickness between the first light guide portion 126 and the second light guide portion 127 constituting the light guide plate 115 is, for example, about 0.00786 mm, and the first unit lens 121A (cylindrical lens). The difference between the height dimension (0.00914 mm) in the first condensing region A1 and the height dimension (0.017 mm) in the second condensing region A2 in 125 and the composite lens 29) is equal. Therefore, the first unit lens 121A has the highest positions (rising ends from the light emitting plate surface 115B) in the first condensing region A1 and the second condensing region A2.

Next, the following comparative experiment 3 was carried out in order to obtain knowledge on how the straightness imparted to the light changes when the apex angle θ7 in the second condensing region A2 of the composite lens 29 is changed. rice field. In Comparative Experiment 3, the apex angle θ7 in the second condensing region A2 of the composite lens 29 was changed in the range of 70 ° to 110 °, and specifically, the apex angle θ7 was changed to 70 °, 80 °, 90 °, It is set to 95 °, 100 °, and 110 °. The light guide plate 115 used in Comparative Experiment 3 has the same configuration as described before this paragraph, except for the numerical value of the apex angle θ7. Then, in the comparative experiment 3, as shown in FIG. 24, the apex angle θ7 in the second condensing region A2 of the composite lens 29 is set to the center position in the X-axis direction with respect to the light guide plate 115 having different apex angles θ7 as described above. After arranging one LED 113, the straightness imparted to the light by the composite lens 29 was verified. Specifically, in Comparative Experiment 3, the brightness of the emitted light emitted from the light emitting plate surface 115B of the light guide plate 115 was measured with one LED 113 lit, and the distance from the incoming light end surface 115A in the Y-axis direction was 3 mm. A luminance distribution in the X-axis direction was created at the position (the straight line L shown by the alternate long and short dash line in FIG. 24). The position at a distance of 3 mm from the incoming light end surface 115A in the Y-axis direction is the display area AA in the non-display area NAA in the Y-axis direction rather than the boundary line between the first condensing area A1 and the second condensing area A2. It is a closer position. An example of the luminance distribution in the X-axis direction is as shown in FIG. The vertical axis of the graph shown in FIG. 25 is relative luminance (no unit). This relative brightness is the front surface when the contact angle θc2 in the second condensing region A2 of the cylindrical lens 25 is 70 ° in the light guide plate 15 according to the first embodiment of the comparative experiments 1 and 2 described in the first embodiment. The brightness (brightness when the position in the X-axis direction is 0 mm) is used as a reference (1.0). The horizontal axis of the graph shown in FIG. 25 represents a position with the central position in the X-axis direction as a reference (0 mm), and the unit thereof is “mm”. Further, among the positive and negative symbols attached to the horizontal axis of the graph shown in FIG. 25, "-(minus)" means the left side in FIG. 24 in the X-axis direction from the reference center position, and "+ ( Plus) ”means the right side in FIG. 24. Luminance distributions in the X-axis direction as shown in FIG. 25 are created for each of the six light guide plates 115 having different apex angles θ7 in the second condensing region A2 of the composite lens 29, and the full width at half maximum, that is, FWHM (FWHM). Full Width at Half Maximum) was extracted and the results are summarized in FIG. The smaller the FWHM value, the more difficult it is for the light to diffuse in the X-axis direction, and the straightness given to the light by the composite lens 29 tends to be higher. It tends to diffuse in the direction, and the straightness imparted to the light by the composite lens 29 tends to be low. FIG. 26 is a graph showing the relationship between the apex angle θ7 and the FWHM in the second focusing region A2 of the composite lens 29. The vertical axis of the graph shown in FIG. 26 is FWHM (unit: “mm”), and the horizontal axis is the apex angle θ7 (unit: “°”) in the second focusing region A2 of the compound lens 29. Further, in FIG. 26, as a comparison target, in the light guide plate 15 according to the first embodiment of the comparative experiments 1 and 2 described in the first embodiment, the contact angle θc2 in the second condensing region A2 of the cylindrical lens 25 is 70. The FWHM value (4.8 mm) extracted from the luminance distribution in the X-axis direction when ° is indicated by a linear broken line.

The experimental results of Comparative Experiment 3 will be described. According to FIG. 26, if the apex angle θ7 in the second condensing region A2 of the composite lens 29 is in the range of 70 ° to 100 °, the comparative experiment 1 in which the contact angle θc2 in the second condensing region A2 is 70 °. It can be seen that the FWHM is smaller than that of Example 1 of 2 and 2. In Example 1 of Comparative Experiments 1 and 2 in which the contact angle θc2 is 70 °, the straightness imparted to the light by the second condensing region A2 in the cylindrical lens 25 is maximized. Therefore, if the apex angle θ7 in the second focusing region A2 of the composite lens 29 is in the range of 70 ° to 100 °, the second focusing region A2 in the light guide plate 15 in which the first unit lens 21A is composed of only the cylindrical lens 25. It can be said that the straightness imparted to the light is higher than that in the case where the straightness imparted to the light is the highest, and the light is less likely to be diffused in the X-axis direction. In particular, when the apex angle θ7 in the second focusing region A2 of the composite lens 29 is in the range of 80 ° to 90 °, the FWHM is kept as small as about 4 mm, and the straightness imparted to light is the highest. It can be said that it is most suitable for increasing the height and making it more difficult for locally bright bright areas to occur in the vicinity of the light entering end surface 115A. On the other hand, if the apex angle θ7 in the second condensing region A2 of the composite lens 29 is smaller than 80 °, the vicinity of the top 29A of the second condensing region A2 in the composite lens 29 when the light guide plate 115 is manufactured by injection molding. The shape reproducibility of the lens is low, and molding tends to be difficult. Therefore, the apex angle θ7 in the second condensing region A2 of the composite lens 29 is in the range of 80 ° to 100 ° to ensure the uniformity of brightness related to the emitted light and to ensure the ease of manufacturing the light guide plate 115. It can be said that it is preferable to do so.

As described above, according to the present embodiment, the plurality of first unit lenses 121A have a plurality of cylindrical lenses 125, and the first condensing region A1 has an arcuate peripheral surface, and the second condensing. Region A2 includes a plurality of composite lenses 29 having a peripheral surface including a top 29A and a pair of hypotenuses 29B sandwiching the top 29A. Compared to the cylindrical lens 125 having an arcuate peripheral surface, the composite lens 29 is repeatedly totally reflected by a pair of hypotenuses 29B sandwiching the top 29A in the second condensing region A2, so that the light is totally reflected with respect to the light. Higher straightness can be imparted. On the other hand, since the composite lens 29 has an arcuate peripheral surface in the first condensing region A1, the straightness imparted to the light in the first condensing region A1 is similar to that of the cylindrical lens 125. Become. By including the composite lens 29 in addition to the cylindrical lens 125 in the plurality of first unit lenses 121A, it is possible to make it more difficult to locally generate a bright bright portion in the second condensing region A2.

Further, the plurality of cylindrical lenses 125 and the composite lens 29 have contact angles θc3 and θc5, which are angles formed by the tangent Ta at the proximal end portion of each peripheral surface in the first condensing region A1 with respect to the second direction. It is said to be the same. In this way, the straightness imparted to the light by the cylindrical lens 125 and the composite lens 29 in the first condensing region A1 becomes equivalent. As a result, even when the arrangement of the plurality of LEDs 113 with respect to the light entering end surface 115A is uneven, it is possible to make it more difficult for a band-shaped dark portion to be generated in the vicinity of the LED 113 far from the light entering end surface 115A.

Further, the plurality of first unit lenses 121A are configured such that the cylindrical lens 125 and the composite lens 29 are alternately and repeatedly arranged in the second direction. In this way, the cylindrical lens 125 and the composite lens 29, which are arranged so as to be arranged alternately and repeatedly, impart different straightness to the light in the second condensing region A2, so that the light is locally arranged in the vicinity of the incoming light end surface 115A. It is possible to make bright bright areas less likely to occur.

Further, in the plurality of composite lenses 29, the angle formed by the pair of hypotenuses 29B in the second condensing region A2 is in the range of 80 ° to 100 °. If the angle formed by a pair of hypotenuses in a plurality of composite lenses is larger than 100 °, the composite lens may be used for light depending on the setting of the contact angle θc4 in the second focusing region A2 of the cylindrical lens 125. The straightness imparted may be lower than the straightness imparted to the light by the cylindrical lens 125. In that respect, if the angle formed by the pair of oblique sides 29B in the second condensing region A2 of the composite lens 29 is 100 ° or less as described above, the contact angle in the second condensing region A2 of the cylindrical lens 125. Regardless of the setting of θc4, the straightness imparted to the light by the composite lens 29 in the second condensing region A2 is higher than the straightness imparted to the light by the cylindrical lens 125. As a result, it is possible to make it more difficult for a bright bright portion to be locally generated in the vicinity of the light entering end surface 115A. On the other hand, if the apex angle in the second condensing region of the composite lens is smaller than 80 °, the shape reproducibility of the vicinity of the apex of the second condensing region in the composite lens will be improved when the light guide plate is manufactured by injection molding. It tends to be low and difficult to manufacture the light guide plate. In that respect, if the apex angle θ7 in the second condensing region A2 of the composite lens 29 is 80 ° or more, when the light guide plate 115 is manufactured by injection molding, the second condensing region A2 in the composite lens 29 The shape reproducibility near the top 29A is kept sufficiently high, whereby the light guide plate 115 can be easily manufactured.

<Other embodiments>
The technology disclosed herein is not limited to the embodiments described above and in the drawings, and for example, the following embodiments are also included in the technical scope.

(1) The first unit lenses 21A and 121A may include an intermediate condensing region (third condensing region) between the first condensing region A1 and the second condensing region A2 in the first direction. No. In that case, the intermediate condensing region imparts straightness to the light propagating in the light guide plates 15 and 115 so as to travel along the first direction, and the straightness is higher than that of the first condensing region A1. However, it is assumed to be lower than the second condensing region A2.

(2) Regarding the arrangement pitch in the X-axis direction of the plurality of first unit lenses 21A and 121A, specific numerical values can be appropriately changed.

(3) The plurality of first unit lenses 21A and 121A may have different arrangement pitchs in the first condensing region A1 and the second condensing region A2. In that case, it is preferable that the first unit lenses 21A and 121A are partially connected to the first condensing region A1 and the second condensing region A2 in order to suppress light leakage, but they are not necessarily connected. good.

(4) The first unit lenses 21A and 121A may be arranged so that the boundary portion between the first focusing region A1 and the second focusing region A2 overlaps with the boundary portion between the display region AA and the non-display region NAA. Further, the second condensing region A2 in the first unit lenses 21A and 121A may be arranged so as to overlap both the display region AA and the non-display region NAA.

(5) The first unit lenses 21A and 121A may include a type other than the cylindrical lenses 25 and 125 and the composite lens 29.

(6) The contact angles θc1 and θc3 in the first condensing region A1 of the cylindrical lenses 25 and 125 may be smaller than 30 ° and larger than 50 °. Similarly, the contact angles θc2 and θc4 in the second condensing region A2 of the cylindrical lenses 25 and 125 may be smaller than 55 ° and larger than 70 °.

(7) Specific numerical values can be appropriately changed with respect to the height dimension and radius of curvature of the first condensing region A1 and the height dimension and radius of curvature of the second condensing region A2 of the cylindrical lenses 25 and 125. be.

(8) The numerical range of the angle θ7 formed by the pair of hypotenuses 29B in the composite lens 29 described in the second embodiment may be, for example, a range of 80 ° to 100 ° (90 ° ± 10 °). Further, the angle θ7 formed by the pair of hypotenuses 29B in the composite lens 29 may be smaller than 80 ° or larger than 100 °.

(9) Specific numerical values can be appropriately changed with respect to the height dimension and the radius of curvature in the first condensing region A1 and the height dimension in the second condensing region A2 in the composite lens 29 described in the second embodiment. Is.

(10) As a modification of the second embodiment, the contact angles θc3 and θc5 in the first condensing region A1 may be different between the cylindrical lens 125 and the composite lens 29.

(11) As a modification of the second embodiment, the number of installations may be different between the cylindrical lens 125 and the composite lens 29.

(12) As a modification of the second embodiment, a plurality of cylindrical lenses 125 and a plurality of composite lenses 29 may be arranged alternately and repeatedly. Further, one of the cylindrical lens 125 and the composite lens 29 may be arranged alternately and repeatedly. Further, the cylindrical lens 125 and the composite lens 29 may be arranged so as to be irregularly arranged.

(13) As a modification of the second embodiment, the first unit lens 121A may exclusively include a plurality of composite lenses 29.

(14) The thickness of the light guide plates 15 and 115 may change stepwise at the boundary between the first light guides 26 and 126 and the second light guides 27 and 127. In that case, the number of steps of the stairs may be one or a plurality.

(15) Regarding the difference in plate thickness between the first light guide portions 26, 126 and the second light guide portions 27, 127 in the light guide plates 15, 115, specific numerical values can be appropriately changed.

(16) The light guide plates 15 and 115 may have the same plate thickness between the first light guide portions 26 and 126 and the second light guide portions 27 and 127. Further, the light guide plates 15 and 115 may have the second light guide portions 27 and 127 thicker than the first light guide portions 26 and 126.

(17) The first lens portion may be provided on the opposite plate surfaces 15C of the light guide plates 15 and 115, and the second lens portion may be provided on the light emitting plate surfaces 15B and 115B of the light guide plates 15 and 115, respectively.

(18) The light emitting light reflecting portion may be provided on the light emitting plate surfaces 15B and 115B of the light guide plates 15 and 115.

(19) In addition to the configuration in which the thicknesses of the light guide plates 15 and 115 are constant over the entire length, the light guide plates 15 and 115 may have a configuration in which the thickness becomes smaller as the distance from the LEDs 13 and 113 increases and the opposite plate surface 15C is inclined. No.

(20) The reflective polarizing sheet 20 may have a structure having a multilayer film without having a polarizing layer. In that case, a polarizing plate having a polarizing layer may be attached to the liquid crystal panel 11 separately from the reflective polarizing sheet 20.

(21) The specific number of laminated optical sheets 17, the order of lamination, the type, and the like can be appropriately changed. For example, the reflective polarizing sheet 20 can be omitted.

(22) The LEDs 13 and 113 may be of the top light emitting type as well as the side light emitting type. Further, it is also possible to use an OLED (Organic Light Emitting Diode) or the like as a light source in addition to the LEDs 13 and 113.

(23) The planar shape of the liquid crystal display device 10 and the backlight device 12 may be a square, a circle, an ellipse, a trapezoid, a rhombus, or the like, in addition to the rectangle. When the planar shape of the backlight device 12 is changed, the planar shape of its constituent members (light guide plates 15, 115, reflective sheet, optical sheet, etc.) may be changed accordingly.

10 ... Liquid crystal display (display device), 11 ... Liquid crystal panel (display panel), 12 ... Backlight device (lighting device), 13,113 ... LED (light source), 15,115 ... Light guide plate, 15A, 115A ... Light end surface, 15B, 115B ... Light emitting plate surface, 15C ... Opposite plate surface, 21A, 121A ... 1st unit lens (condensing part), 22A ... 2nd unit lens (2nd condensing part), 23 ... Light emitting reflection Unit, 23A ... Unit reflection unit, 23A1 ... First reflection surface, 23A2 ... Second reflection surface, 24 ... Inclined surface, 25,125 ... Cylindrical lens, 26,126 ... First light guide unit, 27,127 ... Second Light guide unit, 29 ... Composite lens, 29A ... Top, 29B ... Oblique side, AA ... Display area, A1 ... First condensing area, A2 ... Second condensing area, NAA ... Non-display area, Ta ... tangent line, θc1, θc2, θc3, θc4, θc5 ... Contact angle, apex angle (angle) ... θ7

Claims (15)

A light guide plate that has a plate shape and at least a part of the outer peripheral end surface is a light incoming end surface that allows light to enter, and one plate surface is a light emitting plate surface that emits light.
A plurality of light sources arranged along the incoming light end face,
A light collecting portion provided on one of the light emitting plate surface, which is the opposite plate surface of the light guide plate, and the light emitting plate surface, and is along the normal direction of the light entering end surface. A plurality of light sources extend along the first direction and are arranged side by side along the second direction along the arrangement direction of the plurality of light sources, and the first direction with respect to the light propagating in the light guide plate. It is equipped with a condensing unit that imparts straightness so that it travels along the line.
The plurality of condensing units are arranged on the light source side in the first direction with respect to the first condensing region and the first condensing region, and are higher than the first condensing region with respect to light. A lighting device including a second light collecting region that imparts straightness. The plurality of condensing portions include a plurality of cylindrical lenses having an arcuate peripheral surface.
The plurality of the cylindrical lenses have a contact angle in which the tangent line at the proximal end on the peripheral surface thereof is an angle formed with respect to the second direction in the second focusing region rather than in the first focusing region. The lighting device according to claim 1, which is configured to be large. The plurality of cylindrical lenses have a contact angle in the range of 30 ° to 50 ° in the first focusing region, whereas the contact angle in the second focusing region is 55 ° to 70 °. The lighting device according to claim 2, which is a scope. The lighting device according to claim 2 or 3, wherein the plurality of the condensing units exclusively include the plurality of the cylindrical lenses. The plurality of condensing portions have a plurality of the cylindrical lenses and an arcuate peripheral surface in the first condensing region, and a pair of hypotenuses sandwiching the apex and the apex in the second condensing region. The illuminating device according to claim 2 or 3, wherein a plurality of composite lenses having a peripheral surface including and are included. A plurality of the cylindrical lenses and the composite lens are claimed to have the same contact angle, which is an angle formed by a tangent line at the proximal end portion of each peripheral surface in the first condensing region with respect to the second direction. Item 5. The lighting device according to item 5. The lighting device according to claim 5 or 6, wherein the plurality of condensing units are arranged such that the cylindrical lens and the composite lens are alternately and repeatedly arranged in the second direction. The plurality of composite lenses according to any one of claims 5 to 7, wherein the angle formed by the pair of hypotenuses in the second condensing region is in the range of 80 ° to 100 °. Lighting device. The light guide plate has a first light guide portion in which the first light collecting region of the plurality of light collecting portions is located, and a second light guide plate in which the second light collecting region of the plurality of light collecting portions is located. It has a light guide and
The lighting device according to any one of claims 1 to 8, wherein the second light guide unit has a smaller plate thickness than the first light guide unit. The lighting device according to any one of claims 1 to 9, wherein the plurality of the condensing units have the same arrangement pitch in the second direction in the first condensing region and the second condensing region. .. A second light collecting portion provided on the other side of the opposite plate surface and the light emitting plate surface of the light guide plate, which extends along the first direction and extends along the second direction. Claims 1 to 10 include a second condensing unit that is arranged side by side and imparts straightness so that the light propagating in the light guide plate travels along the first direction. The lighting device according to any one of the above. Light emitting reflecting portions provided on the other side of the opposite plate surface and the light emitting plate surface of the light guide plate, which are arranged at intervals along the first direction to reflect light and reflect the light emitting plate. The lighting device according to any one of claims 1 to 11, further comprising the light emitting reflecting unit including a plurality of unit reflecting units emitted from a surface. Of the opposite plate surface and the light emitting plate surface of the light guide plate, the plate surface on which the light emitting reflecting portion is arranged is arranged so as to be adjacent to the unit reflecting portion in the first direction and is away from the light source. A sloped surface is provided so that the distance from the plate surface where the light source reflecting portion is not installed increases.
In the Idemitsu reflecting portion, the unit reflecting portion is arranged on the light source side in the first direction and is arranged on the opposite side to the first reflecting surface which is inclined with respect to the first direction. It has a second reflective surface that is inclined with respect to the direction.
The lighting device according to claim 12, wherein the light guide plate is configured such that the inclination angle with respect to the first direction increases in the order of the inclined surface, the first reflecting surface, and the second reflecting surface. The lighting device according to any one of claims 1 to 13.
A display device including a display panel that displays using the light from the lighting device. The display panel has a display area on which an image is displayed and a non-display area that surrounds the display area.
The plurality of light-collecting units are arranged so that the first light-collecting area overlaps with both the display area and the non-display area, and the second light-collecting area overlaps with the non-display area. 14. The display device according to claim 14.

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